Kōsuke

was a young toad that wore goggles. On Kōsuke's back is the kanji word for.

Personality
He seemed to be a very happy and cheerful toad, and took orders almost directly.

Invasion of Pain arc
When Naruto goes to Myōbokuzan to train, Kōsuke is left in Konoha so that he can inform Naruto of when Pain comes looking for him. When Pain finally attacks, Kōsuke is killed by Danzō before he can return to Myōbokuzan so that Naruto will not know to come back. Naruto eventually finds out anyway when the toads notice Kōsuke's name missing from the toad summoning contract.