Talk:Mito Mitsukuni/@comment-27194838-20191105182009/@comment-10330822-20191106015459

She also said

"Oh, it's Mito-tan. Hiding her desolate chest like that is a good decision isn't it."

Arisa pompously criticized Mito over my shoulders. (WN 14-1)

Since she was in her disguise, I'd chalk it up to part of the disguise. That or she is not complete flat-chested, at the "swelling" is more referring to the difference between her chest and Satou's which is obviously even flater.