@Bluefox_1 That actually makes a lot of sense, the refrigerator could indicate her amassing money in order to hire a detective, but rikai not taking payment in money left it free to be used. This would be the best infiltration she could do in that scenary. But i think the two year gap should have some relevance too, i'm still picturing it out. This is turning out to be a pretty interesting one, i like these kind of stories, though it's pretty hard to find decent ones.
@Meowzilla idk, I only read the first one ¯\_(ツ)_/¯
The first volume isn't much different from the manga, except that it's a bit more detailed, of course.
And to begin with, they aren't even translated into English.
im gonna expand on my theory from 2 chapters ago and say hes the client, he keeps having episodes and it could be he suppresing his own memories, but probably in one of those episodes he contacted the girl to investigate for her