The following furniture will change with the season.

Do note that those changes are arbitrary and may not happen at the same time each year, if at all.

Chair+Desk

Admiral's Mahjong Table

The "Admiral's Mahjong Table" (提督の麻雀卓) will change depending on the season:

Season	Look	Picture
Winter	Snow patterns kotatsu futon (Clicking on the cat's tail produces a reaction)
Setubun	Setsubun-themed kotatsu futon (Clicking on the cat's tail produces a reaction)
Summer	No kotatsu futon & simple sake
Fall	No kotatsu futon & twin sake

Hot Spring Hinoki Bath

The "Hot Spring Hinoki Bath" (温泉檜風呂) will change depending on the season:

Season	Look	Picture
Spring	Sakura & tea
Rainy season	Hydrangea
Fall	Red maple leafs & tea / susuki & sake
2021	Sake
?	Blanc

Hot Spring Stone Bath

The "Hot Spring Stone Bath" (温泉岩風呂) will change depending on the season:

Season	Look	Picture
Spring	Sakura /& sake
Rainy season	Hydrangea
Summer	Sunflowers
Fall	Red maple leafs /& sake / susuki
Winter	Nanten & mikans
?	Sake

Admiral's New Year's Big Splish-Up

The "Admiral's New Year's Big Splish-Up" (年末年始の提督大奮発) will change depending on the season:

Season	Look	Picture
01/01-01/07	Ozoni
01/07-12/26	Rice porridge with seven herbs
12/27-12/31	New Year's Eve soba noodles

Café Table Set

The "Café Table Set" (Caféテーブルセット) will change depending on the season:

Season	Look	Picture
Normal	Pancakes
Zuiun Festival	Pancakes & Zuiun
White Day	?
Halloween	Pumpkin cakes
Christmas	Xmas cakes
?	?	150px

Coastal Defense Ships' General-purpose Circular Desk

The "Coastal Defense Ships' General-purpose Circular Desk" (海防艦の汎用円形机) will change depending on the season:

Season	Look	Picture
New Year	Ozoni, Kadomatsu, and ink writing
Setsubun?	?
Valentine's Day	Chocolate making
White Day	White Day
Autumn	Chestnuts cracking and writing/drawing
Christmas	Wmass foods and decorations
New Year's Eve	New year soba

Mikans and a Custom-made Naval Base Chabudai Table

The "Mikans and a Custom-made Naval Base Chabudai Table" (蜜柑と特注鎮守府ちゃぶ台) will change depending on the season:

Season	Look	Picture
Fall	Green tea & fried rice?
Spring/Summer	Strawberies sweets
Christmas	Strawberies cake
New Year	New's year soba

Admiral and Ooyodo Secretary Desk

The "Admiral and Ooyodo Secretary Desk" (提督と大淀秘書机) will change depending on the season:

Season	Look	Picture
Fall	Cosmos & ? , mikans & tea
Rainy Season	Hydrangeas, cakes & tea
?	?	150px

Admiral and 3rd Squadron Table

The "Admiral and 3rd Squadron Table" (提督と第三戦隊のテーブル) will change depending on the season:

Season	Look	Picture
Fall	Kirishima's stuff & mikan cake
Winter	?	150px
Spring	?	150px
Summer	?	150px

Windows+Curtains

Naval Base Counter Bar

The Naval Base Counter Bar's food will change depending on the season.

See here.

Mini Kadomatsu and Zodiac Window

The "Mini Kadomatsu and Zodiac Window" (ミニ門松と干支の窓) will change depending on the year:

Year	Picture
Ox
Tiger	200px
Rabbit
Dragon

Submarine Squadron Window

The "Submarine Squadron Window" (潜水艦隊の窓) will change depending on the season:

Season	Look	Picture
New Year	? & Kadomatsu
Autumn	Mapple leafs & chestnuts
Summer	Sunflowers & ice
Setsubun	? & Setsubun beans
?	? & rice porridge with seven herbs
Christmas	Poinsettia & Xmass decorations, cakes and gifts
New Year's Eve	New Year's Eve soba noodles
?	?
?	?	200px

Haruna's White Window

The "Haruna's White Window" (榛名の白い窓) will change depending on the season:

Season	Look	Picture
Autumn	Mapple leafs & ?
?	? & coffee
?	?	200px

Mainstay of Mainstay Seasonal Window

The "Mainstay of Mainstay Seasonal Window" (主力オブ主力な季節の窓) will change depending on the season:

Season	Picture
Setsubun
Autumn
	200px

Decoration

Japanese Cherry Blossom Arrangement

The "Japanese Cherry Blossom Arrangement" (桜の和のアレンジメント) will change depending on the season:

Season	Look	Picture
03/23～03/25	Buds
03/25～03/28	50% in bloom (animated when clicked-on)
03/28～04/08	75% in bloom (animated when clicked-on)
04/09～03/22	Full bloom (animated when clicked-on)
04/9～??	Leafed cherry blossoms (animated when clicked-on)
?	Leafed