Did I find a bug or am I confused?

[Beldraketh]

I went to find isshin, but he wasn't in his room. So I found out I had to do the rat quest, I followed a youtube guide talked to the guy got the quest, he goes on about some move ability. Anyway! I do the quest, kill the rats. But he won't let me turn it in, he keeps saying the same thing over and over, I tried resting and trying it again about 3 times still no luck! :( I checked the magical box for his move back at the temple as well and it was empty, what am I missing?

[HighLanderPony]

You turn that in at Tengu. Close to Castle Gate idol, next to the mob merchant, indoors.