I really liked this. I wouldn't be surprised if yashiro did actually have a gender identity issue and momo is one of those guys that is just really nice and accepting of that.
I think that momo is the type that if he was dating a girl and she told him that she used to be a guy but got surgery, he would be like 'Okay' and continue loving them just the same.
I don't know if that's what was intended, I just feel that's plausible for momo's personality type.
Udagawachou De Mattete Yo.