Eiji Usatsuka (兎塚 エイジ, Usatsuka Eiji, born August 16 in Osaka Prefecture, Japan) is a Japanese light novel illustrator. He is notable for the illustration for the series Zero no Tsukaima. He illustrates insert images for many novels.
After university graduation he was employed as illustrator by the visual novel publisher Visual Art's using the pseudonym Sawagani (サワガニ, Japanese Freshwater Crab). As side job he made illustrations for light novels which is against the company policy. The similarity of "both peoples" designs, were however noticed and later revealed by Tōya Okano (scenario assistant for Visual Art's' Clannad) in a Dengeki G's Magazine interview article presenting Visual Art's brand Mana’s game Angel Magister.
Novels and other works he contributed his illustrations to include:
- 兎塚エイジとは - はてなダイアリー
- 「ゼロの使い魔」の兎塚エイジ氏がエロゲデビュー！ その意外な真相とは. Half Moon Diary (in Japanese). 2008-12-26. Archived from the original on 2009-04-08. Retrieved 2009-06-01. CS1 maint: discouraged parameter (link)
- "Main Staff". Angel Magister Official Site (in Japanese). mana/visualart's. Archived from the original on 2009-06-02. Retrieved 2009-06-01. CS1 maint: discouraged parameter (link)