Fastest Japanese destroyer, Shimakaze (72km/hr) 39 knots

According to reference: light cruiser-era Mogami 37 knots

Fastest light cruisers Kuma-class and Nagara-class 36 knots

Fastest heavy cruisers (pre-remodelling)Myouko and Takao-class

Fastest carrier Hiryuu

Torpedo-cruisers

Slowest destroyer with combat load. Akizuki (Though Matsu and Tachibana were 27.8 knots)

Slowest heavy cruisers, Furutaka and Kako (after remodelling) (9 Knots while Yakumo)

Slowest light cruisers Tenryuu-class (Though Yasoshima was 22 knots)

Fastest Battleship (After second remodel) Haruna

Slowest carrier Houshou

Slowest Battleship Yamashiro (after large scale remodel.)

Reference: With Kaiten, Kitakami

i-19 surfaced: 23.6 knots; submerged 8 knots.

Akitsumaru

Akashi

I-401: surfaced 18.5 knots; submerged 6.5 knots. As trivia, I-58 was 17.7 knots surfaced.

Katori

Reference: during her era as a practice ship: Hiei

Irako

Mamiya

Maruyu I type 18.5km/hr; surfaced 10knots; submerged 4 knots.

Pre-remodel Taiyou, Un'you, Chuuyo, and Shinyo were 21 knots.