Yobuko is a Summer-type crocodile Makamou and an antagonist in Kamen Rider Hibiki.
Kamen Rider Hibiki
A normal Yobuko appeared at Saitama and was later confronted by Ibiki. It was destroyed along with several other Makamou by Ibuki with his Shippuu Issen.
Another Yobuko later appeared at Sano and faced off against Todoroki. Todoroki destroyed Yobuko alongside a Tengu with Raiden Gekishin.
Kamen Rider Decade
The leader of the Vigilantes' was transformed into a Yobuko by Llumu Qhimil using the powers of both the GiGi and GaGa armlets as a reward for his service.