Considering he'd ended up being the hind parts with the best girl's rear part in front of him while singing and sweating, that counts as a blessing rather than a somewhat precarious situation.
I know this costume. For it to work, he has to hold her butt while bending over. Or she has to hold his butt while bending over. But most likely he is holding her butt because she has to sing.
I feel like all the people in this manga are way too sloppy about hiding their 'secrets'...it's kind of amazing that the MC is the only one finding them out.
To be fair, most people irl pay hardly any attention at all to their surroundings..
Just look at how common those statements about nothing ever happening are.
You'd think he'd have just gone "Yo I'm gonna be on a night hike, catch some air by myself, I'll be back at 10" or something. But then he wouldn't have been able to huck a knife at someone while yelling DARE DA, so it all worked out I guess?