diff --git a/docs/.vitepress/assets/home-cover-2025-12-24-bg.avif b/docs/.vitepress/assets/home-cover-2025-12-24-bg.avif
new file mode 100644
index 000000000..ba0c239e1
Binary files /dev/null and b/docs/.vitepress/assets/home-cover-2025-12-24-bg.avif differ
diff --git a/docs/.vitepress/assets/home-cover-2025-12-24.avif b/docs/.vitepress/assets/home-cover-2025-12-24.avif
new file mode 100644
index 000000000..16ff575c5
Binary files /dev/null and b/docs/.vitepress/assets/home-cover-2025-12-24.avif differ
diff --git a/docs/.vitepress/components/Home.vue b/docs/.vitepress/components/Home.vue
index 288a58a48..5894b32a4 100644
--- a/docs/.vitepress/components/Home.vue
+++ b/docs/.vitepress/components/Home.vue
@@ -6,15 +6,21 @@ import { createAnimatable } from 'animejs'
 import { onMounted, shallowRef, useTemplateRef, watch, watchEffect } from 'vue'
 import { useI18n } from 'vue-i18n'
 
+import homeBackgroundChristmas20251224 from '../assets/home-cover-2025-12-24-bg.avif'
 // NOTICE: for unknown reasons, without `?no-inline`, the inlined SVG use in the SFC template
 // of `url(...)` doesn't work properly in Vite/Vue, the entire SVG content either got incorrectly
 // cached or erased in dev/prod, causing the mask pattern to not show up.
 import homeBackgroundPatternGhost from '../assets/home-patterns-ghost.svg?no-inline'
 import homeBackgroundPatternLollipop from '../assets/home-patterns-lollipop.svg?no-inline'
 import ParallaxCover from './ParallaxCover.vue'
+import ParallaxCoverChristmas20251224 from './ParallaxCoverChristmas20251224.vue'
 import ParallaxCoverHalloween20251029 from './ParallaxCoverHalloween20251029.vue'
+import Snowfall from './Snowfall.vue'
 
-import { isBetweenHalloweenAndHalfOfNovember } from '../composables/date'
+import {
+  isBetweenChristmasAndHalfOfJanuary,
+  isBetweenHalloweenAndHalfOfNovember,
+} from '../composables/date'
 
 const heroRef = useTemplateRef<HTMLDivElement>('hero')
 
@@ -106,6 +112,19 @@ watchEffect((onCleanup) => {
               >
                 <div i-twemoji:jack-o-lantern />Happy Halloween!<div i-twemoji:jack-o-lantern />
               </div>
+              <div
+                v-if="true || isBetweenChristmasAndHalfOfJanuary(new Date())"
+                :class="[
+                  'w-fit',
+                  'flex items-center gap-2',
+                  'px-4 py-1',
+                  'mb-3 sm:mb-4 lg:mb-8',
+                  'border-3 rounded-full border-white/75 bg-red-300/75 text-neutral-800 dark:border-white/50 dark:bg-red-500/50 dark:text-white',
+                  'text-sm sm:text-base align-middle',
+                ]"
+              >
+                <div i-twemoji:christmas-tree />Merry Christmas!<div i-twemoji:christmas-tree />
+              </div>
               <div :class="[isBetweenHalloweenAndHalfOfNovember(new Date()) ? 'font-sans-serif-halloween' : '']">
                 Project AIRI
               </div>
@@ -165,16 +184,28 @@ watchEffect((onCleanup) => {
         <template v-if="isBetweenHalloweenAndHalfOfNovember(new Date())">
           <div class="bg-icon-pattern pointer-events-none absolute inset-0 z-0 opacity-10 dark:opacity-10" :style="{ '--bg-mask-icon-pattern': `url(${homeBackgroundPatternGhost})` }" />
         </template>
+        <template v-if="isBetweenChristmasAndHalfOfJanuary(new Date())">
+          <img :src="homeBackgroundChristmas20251224" class="pointer-events-none absolute inset-0 z-0 h-full w-full object-cover">
+        </template>
         <template v-else>
           <div class="bg-icon-pattern pointer-events-none absolute inset-0 z-0 opacity-10 dark:opacity-10" :style="{ '--bg-mask-icon-pattern': `url(${homeBackgroundPatternLollipop})` }" />
         </template>
-      </ClientOnly>
-      <!-- Flickering red (even within the color space range) if to top in oklch (UnoCSS or tailwind css default), have to force to use srgb color space to prevent this -->
-      <div class="absolute bottom-0 left-0 right-0 top-0 z-2 h-80% from-transparent to-white bg-gradient-to-t dark:to-[hsl(207_15%_5%)]" style="--un-gradient-shape: to top in srgb;" />
-      <ClientOnly>
+        <!-- Flickering red (even within the color space range) if to top in oklch (UnoCSS or tailwind css default), have to force to use srgb color space to prevent this -->
+        <div
+          :class="[
+            'absolute bottom-0 left-0 right-0 top-0 z-2',
+            'from-transparent to-white bg-gradient-to-t dark:to-[hsl(207_15%_5%)]',
+            isBetweenChristmasAndHalfOfJanuary(new Date()) ? 'h-[40%]' : 'h-[80%]',
+          ]"
+          style="--un-gradient-shape: to top in srgb;"
+        />
         <template v-if="isBetweenHalloweenAndHalfOfNovember(new Date())">
           <ParallaxCoverHalloween20251029 />
         </template>
+        <template v-else-if="isBetweenChristmasAndHalfOfJanuary(new Date())">
+          <Snowfall />
+          <ParallaxCoverChristmas20251224 />
+        </template>
         <template v-else>
           <ParallaxCover />
         </template>
@@ -182,7 +213,7 @@ watchEffect((onCleanup) => {
     </div>
 
     <footer class="fixed bottom-3 left-1/2 z-40 flex justify-end -translate-x-1/2">
-      <div class="rounded-full bg-white/80 px-3 py-2 text-sm text-slate-400 backdrop-blur-md dark:bg-white/20 dark:text-slate-900" text="nowrap">
+      <div class="rounded-full bg-white/80 px-3 py-2 text-sm text-slate-700 backdrop-blur-md dark:bg-white/20 dark:text-slate-900" text="nowrap">
         Since 2024 @ <a href="https://github.com/proj-airi">Project AIRI</a> × <a href="https://github.com/moeru-ai">萌える AI 研究会</a>
       </div>
     </footer>
diff --git a/docs/.vitepress/components/ParallaxCoverChristmas20251224.vue b/docs/.vitepress/components/ParallaxCoverChristmas20251224.vue
new file mode 100644
index 000000000..e16a73970
--- /dev/null
+++ b/docs/.vitepress/components/ParallaxCoverChristmas20251224.vue
@@ -0,0 +1,107 @@
+<script setup lang="ts">
+import type { AnimatableObject } from 'animejs'
+
+import { useLocalStorage } from '@vueuse/core'
+import { createAnimatable } from 'animejs'
+import { onMounted, shallowRef, useTemplateRef, watchEffect } from 'vue'
+
+import homeCover from '../assets/home-cover-2025-12-24.avif'
+
+const surfaceRef = useTemplateRef<HTMLImageElement>('surface')
+const silhouetteLayer1Ref = useTemplateRef<HTMLDivElement>('silhouetteLayer1')
+const silhouetteLayer2Ref = useTemplateRef<HTMLDivElement>('silhouetteLayer2')
+
+const shouldReduceMotion = useLocalStorage('docs:settings/reduce-motion', false)
+
+const DURATION = 1200
+const EASE = 'outSine'
+
+const surfaceAnimatable = shallowRef<AnimatableObject>()
+const silhouetteLayer1Animatable = shallowRef<AnimatableObject>()
+const silhouetteLayer2Animatable = shallowRef<AnimatableObject>()
+
+function animateCover(xOffsetRatio: number, yOffsetRatio: number) {
+  const referenceWidth = window.innerWidth
+
+  surfaceAnimatable.value?.x?.(-xOffsetRatio * 0.02 * referenceWidth)
+  surfaceAnimatable.value?.y?.(-yOffsetRatio * 0.02 * referenceWidth)
+  surfaceAnimatable.value?.z?.(0)
+
+  silhouetteLayer1Animatable.value?.x?.(0.01 * referenceWidth - yOffsetRatio * 0.015 * referenceWidth)
+  silhouetteLayer1Animatable.value?.y?.(0.02 * referenceWidth + xOffsetRatio * 0.015 * referenceWidth)
+  silhouetteLayer1Animatable.value?.z?.(0)
+
+  silhouetteLayer2Animatable.value?.x?.(0.01 * referenceWidth + yOffsetRatio * 0.01 * referenceWidth)
+  silhouetteLayer2Animatable.value?.y?.(-0.01 * referenceWidth - yOffsetRatio * 0.01 * referenceWidth)
+  silhouetteLayer2Animatable.value?.z?.(0)
+}
+
+function onMouseMove(event: MouseEvent) {
+  const x = event.clientX
+  const y = event.clientY
+
+  const xOffsetRatio = (x - window.innerWidth / 2) / window.innerWidth
+  const yOffsetRatio = (y - window.innerHeight / 2) / window.innerHeight
+
+  animateCover(xOffsetRatio, yOffsetRatio)
+}
+
+onMounted(() => {
+  const animatableConfig = {
+    x: DURATION,
+    y: DURATION,
+    z: 0,
+    ease: EASE,
+  }
+
+  surfaceAnimatable.value = createAnimatable(surfaceRef.value!, animatableConfig)
+  silhouetteLayer1Animatable.value = createAnimatable(silhouetteLayer1Ref.value!, animatableConfig)
+  silhouetteLayer2Animatable.value = createAnimatable(silhouetteLayer2Ref.value!, animatableConfig)
+})
+
+watchEffect((onCleanup) => {
+  if (shouldReduceMotion.value) {
+    animateCover(0, 0)
+  }
+  else {
+    if (!import.meta.env.SSR) {
+      window.addEventListener('mousemove', onMouseMove)
+      onCleanup(() => {
+        window.removeEventListener('mousemove', onMouseMove)
+      })
+    }
+  }
+})
+
+const maskImageURL = `url(${homeCover})`
+</script>
+
+<template>
+  <div
+    :class="[
+      'relative left-1/2 -translate-x-1/2 max-w-none z-1',
+      'w-[160%] translate-y-[35%] translate-x-[-55%] scale-100 -rotate-0 top-5rem',
+      'md:w-[150%] md:translate-y-[40%] md:rotate-[0deg] md:top-8dvh',
+      'lg:w-[95%] lg:translate-y-[-20%] lg:translate-x-[-50%] lg:rotate-[0deg] lg:scale-95 lg:top-32dvh',
+      'xl:translate-y-[-50%] xl:translate-x-[-50%] xl:scale-80 xl:top-18dvh',
+      '2xl:w-[100%] 2xl:translate-y-[-20%] 2xl:translate-x-[-50%] 2xl:rotate-[0deg] 2xl:top-16dvh',
+    ]"
+  >
+    <img ref="surface" :src="homeCover" alt="Project AIRI Cover Image" class="w-full object-cover">
+  </div>
+</template>
+
+<style scoped>
+.silhouette {
+  -webkit-mask-image: v-bind(maskImageURL);
+  mask-image: v-bind(maskImageURL);
+  -webkit-mask-mode: alpha;
+  mask-mode: alpha;
+  -webkit-mask-size: contain;
+  mask-size: contain;
+  -webkit-mask-repeat: no-repeat;
+  mask-repeat: no-repeat;
+  -webkit-mask-position: center; /* Center the mask */
+  mask-position: center;
+}
+</style>
diff --git a/docs/.vitepress/components/Snowfall.vue b/docs/.vitepress/components/Snowfall.vue
new file mode 100644
index 000000000..53e11cf16
--- /dev/null
+++ b/docs/.vitepress/components/Snowfall.vue
@@ -0,0 +1,175 @@
+<!--
+Author:  hyperstown <64496017+hyperstown@users.noreply.github.com>
+License: MIT License
+
+Source code: https://github.com/hyperstown/pure-snow.js
+https://codepen.io/YusukeNakaya/pen/NWPqvWW
+https://codepen.io/alphardex/pen/dyPorwJ
+-->
+
+<script setup lang="ts">
+import { useEventListener, useLocalStorage } from '@vueuse/core'
+import { onMounted, useTemplateRef, watchEffect } from 'vue'
+
+const shouldReduceMotion = useLocalStorage('docs:settings/reduce-motion', false)
+
+const snowContainer = useTemplateRef<HTMLDivElement>('snowContainer')
+
+const SNOWFLAKE_COUNT = 160
+const STYLE_ELEMENT_ID = 'snowfall-dynamic-css'
+
+function randomInt(max = 100) {
+  return Math.floor(Math.random() * max) + 1
+}
+
+function randomIntRange(min: number, max: number) {
+  const ceilMin = Math.ceil(min)
+  const floorMax = Math.floor(max)
+
+  return Math.floor(Math.random() * (floorMax - ceilMin + 1)) + ceilMin
+}
+
+function randomBetween(min: number, max: number) {
+  return Math.random() * (max - min) + min
+}
+
+function getHeights() {
+  const bodyHeightPx = document.body.offsetHeight || window.innerHeight
+  const pageHeightVh = (100 * bodyHeightPx) / window.innerHeight
+
+  return { bodyHeightPx, pageHeightVh }
+}
+
+function ensureStyleElement() {
+  let styleEl = document.getElementById(STYLE_ELEMENT_ID) as HTMLStyleElement | null
+  if (!styleEl) {
+    styleEl = document.createElement('style')
+    styleEl.id = STYLE_ELEMENT_ID
+    document.head.appendChild(styleEl)
+  }
+
+  return styleEl
+}
+
+function generateSnowCSS(count: number, pageHeightVh: number) {
+  let rule = ''
+  const snowflakeName = 'snowflake'
+
+  for (let i = 1; i <= count; i++) {
+    const randomX = Math.random() * 100 // vw
+    const randomOffset = Math.random() * 10 // vw
+    const randomXEnd = randomX + randomOffset
+    const randomXEndYoyo = randomX + randomOffset / 2
+    const randomYoyoTime = randomBetween(0.3, 0.8)
+    const randomYoyoY = randomYoyoTime * pageHeightVh // vh
+    const randomScale = Math.random()
+    const fallDuration = randomIntRange(10, (pageHeightVh / 10) * 3) // s
+    const fallDelay = randomInt((pageHeightVh / 10) * 3) * -1 // s
+    const opacity = Math.random()
+
+    rule += `
+      .${snowflakeName}:nth-child(${i}) {
+        opacity: ${opacity};
+        transform: translate(${randomX}vw, -10px) scale(${randomScale});
+        animation: fall-${i} ${fallDuration}s ${fallDelay}s linear infinite;
+      }
+
+      @keyframes fall-${i} {
+        ${randomYoyoTime * 100}% {
+          transform: translate(${randomXEnd}vw, ${randomYoyoY}vh) scale(${randomScale});
+        }
+        to {
+          transform: translate(${randomXEndYoyo}vw, ${pageHeightVh}vh) scale(${randomScale});
+        }
+      }
+    `
+  }
+
+  ensureStyleElement().textContent = rule
+}
+
+function clearSnow() {
+  const container = snowContainer.value
+  if (!container)
+    return
+
+  container.innerHTML = ''
+}
+
+function generateSnowflakes(count: number) {
+  const container = snowContainer.value
+  if (!container)
+    return
+
+  container.innerHTML = ''
+
+  for (let i = 0; i < count; i++) {
+    const flake = document.createElement('div')
+    flake.className = 'snowflake'
+    container.appendChild(flake)
+  }
+}
+
+function createSnow() {
+  const container = snowContainer.value
+  if (!container)
+    return
+
+  const count = Number(container.dataset.count || SNOWFLAKE_COUNT)
+  const { pageHeightVh } = getHeights()
+
+  generateSnowCSS(count, pageHeightVh)
+  generateSnowflakes(count)
+}
+
+onMounted(() => {
+  if (import.meta.env.SSR)
+    return
+
+  createSnow()
+})
+
+watchEffect(() => {
+  if (import.meta.env.SSR)
+    return
+
+  const handleResize = () => createSnow()
+
+  if (shouldReduceMotion.value) {
+    clearSnow()
+    snowContainer.value?.style.setProperty('display', 'none')
+  }
+  else {
+    snowContainer.value?.style.removeProperty('display')
+    createSnow()
+    useEventListener('resize', handleResize)
+  }
+})
+</script>
+
+<template>
+  <div
+    ref="snowContainer"
+    :class="[
+      'docs-theme-christmas-2025-12-24-snowfall',
+      'pointer-events-none',
+      'fixed',
+      'inset-0',
+      'z-100',
+      'overflow-hidden',
+    ]"
+    aria-hidden="true"
+  />
+</template>
+
+<style>
+.docs-theme-christmas-2025-12-24-snowfall .snowflake {
+  position: absolute;
+  width: 12px;
+  height: 12px;
+  border-radius: 9999px;
+  background: rgba(255, 255, 255, 0.9);
+  box-shadow: 0 0 8px rgba(255, 255, 255, 0.35);
+  will-change: transform;
+}
+</style>
diff --git a/docs/.vitepress/composables/date.ts b/docs/.vitepress/composables/date.ts
index 92ba42050..83d0637e7 100644
--- a/docs/.vitepress/composables/date.ts
+++ b/docs/.vitepress/composables/date.ts
@@ -7,3 +7,11 @@ export function isBetweenHalloweenAndHalfOfNovember(date: Date) {
 
   return isAfter(date, halloween) && isBefore(date, halfOfNovember)
 }
+
+export function isBetweenChristmasAndHalfOfJanuary(date: Date) {
+  const year = date.getFullYear()
+  const christmas = new Date(year, 11, 20) // December 20
+  const halfOfJanuary = new Date(year + 1, 0, 10) // January 10 of the next year
+
+  return isAfter(date, christmas) && isBefore(date, halfOfJanuary)
+}