I wouldn't want to say he's gathering outside power, as much as he's still recovering his own.

I think it would be good to start with them attending a funeral. We could have some of the students there still in uniform, maybe it's taking place on a Monday night? If I recall, their academy runs pretty long, like 8-5 or something. So if Botan shows up in the school's uniform, it would indicate not only her involvement as a reaper but that she's going to go undercover at his school as well.