The childhood friend in the opposite room concealed her affair from her fiancé before her wedding, a story of depraved and muddy sex. (Igarashi Natsu FSDSS-463)

Xia, my childhood friend whom I always liked during my school days, returned to her hometown with her fiancé one day. I, who used to spy on her every day through my window during my school days, couldn't stand seeing her naked and forced Xia to cross a line...