The following furniture will change depending on the current Secretary.

Flooring

Mysterious Xmas Carpet

The "Mysterious Xmas Carpet" (謎のXmasカーペット) will have some pets roaming around some secretaries:

Secretary	Pet	Picture
Richelieu-class Commandant Teste	Octopus
USN FBB/BB/CV/CVB	Nevada's Goat
Gotland Yura	Gotland's sheep
Oboro Akebono Sazanami Oshio	Oboro's crab
Souya	Taro and Jiro (Sakhalin huskies)
Others	Nothing	-

The "Secretary and Admiral's Desks" (秘書艦と提督の机) will change depending on the secretary:

Secretary	Desk
German ships, Shinyou, Italian ships, I-503, I-504, American ships, Richelieu, Commandant Teste, De Ruyter
Kongou-class, Yamato-class, Unyou, Makinami, Momo, British ships, Perth, Gotland, Jean Bart, Gloire, Mogador, Gangut, Tashkent
Drum, all others

The "Desk for Two to Enjoy the Rainy Season" (梅雨を楽しむ二人の机) food will change depending on the secretary:

The "Admiral and Escort Carrier Desk" (提督と護衛空母の机) ornament will change depending on the secretary:

The "Secretary and Admiral's Desk with Irises and Kashiwamochi" (菖蒲と柏餅の提督秘書机) drinks will change depending on the secretary:

Secretary	Drink	Picture
German ships, Shinyou, Italian ships, I-503, I-504, American ships, Richelieu, Commandant Teste, De Ruyter	Coffee pot
Kongou-class, Yamato-class, Unyou, Makinami, Momo, British ships, Perth, Gotland, Jean Bart, Gloire, Mogador, Gangut, Tashkent	Black tea and teapot
Drum, all others	Green tea and teapot

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

The "Windy Window Waiting for Rainy Season's End" (梅雨明け待ちの風の窓) will have different curtain holdings depending on the secretary:

Secretary	Drink	Picture
others	Teru Teru Bouzu
Amatsukaze	Amatsukaze twin-tails' streamers

The "Amatsukaze's Nice Personal Storage Shelf" (天津風のいい風私物棚) will have different sets of clothes depending on the secretary:

Secretary	Drink	Picture
others	Amatsukaze's uniform
Amatsukaze Kai Ni	Amatsukaze Kai Ni's uniform

The "Coastal Defense Ship's May Decoration" (海防艦の五月飾り) will have a different 1st plush depending on the secretary:

Secretary	1st plushe	Picture
Shiratsuyu-class Matsu-class Mikura-class	Kurahashi
CA/CAV Type D Kaiboukan	Kaiboukan No.4
CV(B/L) Ukuru-class	Inagi
BBV CL/CLT Hiburi-class	Daitou
BB/FBB Hatsuharu-class Shimushu-class	Hachijou
Etorofu-class Other ships	Sado

The "Inagi's Personal Belongings Shelf" (稲木の私物小棚) will have a different set depending on the secretary:

Secretary	Drink	Picture
others	Inagi's uniform & belongings
Inagi Kai Ni	Inagi Kai Ni's & belongings

The "Dressing Room" (脱衣所) will have different sets of clothes depending on the secretary:

The "Ship Girls' Umbrella Stand" (艦娘の傘立て) will have different versions depending on the secretary:

There are 3 Umbrella stands depending on the secretary type,
During the rainy season, ships with limited rainy season CG who have their umbrella (or other related item) in the stand will "take it" when set as secretary, removing it from the stand.

Secretary	List of Item Owners	Umbrella Stand
DE/Souya	Souya, Fukae, Etorofu, Hirato, Kaiboukan No.4, Kaiboukan No.30
DD	Minazuki, Usugumo, Sagiri, Akebono, Sazanami, Yuudachi, Murasame, Takanami, Fujinami, Hayanami, Hamanami, Hayashimo, Kiyoshimo, Tamanami, Libeccio, Scirocco, Heywood
Others	Fusou, Haruna, Shouhou, Gambier Bay, Chitose, Chiyoda, Kako, Ooi, Yuubari, Ooyodo, I-203, Mizuho, Kamoi, Tuscaloosa, Gotland