Apocalypse: I Built the Infinite Train - Chapter 260: Three-kilometer Battle Line

The Student Council President’s Secret Laid Bare (生徒会長のセキ裸ラな秘密) is fairly standard 2D Dream Bunko fare but with an exhibitionism theme.

Basically, it’s about a guy who discovers the student council president is an exhibitionist and gets roped into helping her with that fetish.

She is the underworld Ghost Doctor’s only disciple, who accidentally transmigrated into the body of the main wife’s daughter in the general’s mansion. She used to be a punching bag.Now, she stepped on her dregs of an older sister, put her father’s concubine in her place, and teaches any objectionable aristocratic ladies a lesson.

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

Mo Yan was an illegitimate child of a rich family and was arranged by her mother to take the place of her sister in marriage to a poor man in order to fulfill the marriage contract set by the previous generation, allowing the Mo family to get their hands on that substantial dowry.