Gangi-kozo - 岸涯小僧 - [yokai]
• About this yokai: a hairy river kappa known for its particuarly long sharp teeth & for hanging around fishing peirs by the rivers edge. - it eats fish, which it often greedily consumes, head first. when fisherman encounter one, they throw it their biggest catch, and then run away asap!!!
[as it appears in Toriyama Sekiens, Gazu hyakki yagyo 
• History & early appearances: Gangi kozo's earliest mention & Original appearance was a part of Toriyama Sekien's Gazu hyakki yagyo Shui  not much is written other than its got sharp teeth & that it enjoys eating fish, most of its lore is assumed from its name. - Short stone peirs leading down to waters edges are also known as "Gangi" and the "Kozo" is a nick name for "young monks." (its sorta like saying 'youngster') - According to Mizuki Shigeru, it can also be called "Gear-tooth" (雁木小僧.) particularly because of how its sharp teeth are: a "Gangi-yashuri" is a rough, chizel like tool commonly used in netsuke carving, woodworking & carpentry.
Even though this is the only early mention of "gangi-kozo" as a yokai in particular. There are several similarly described kappa with hairy appearances & sharp teeth, as such it's often said to be yet another transitional form of kappa.
see also: kappa variants.