Chained soldier

"Decades ago, gates to an otherworldly and dangerous dimension known as Mato--the "Demon City"--appeared across Japan. Those who partook in the "peaches" growing there gained unique abilities--but only if they're girls. When down-in-the-dumps high school boy Yuuki Wakura finds himself caught up in a gate, he's saved by Kyouka Uzen, the beautiful commander of the 7th squad of the Demon Defense Force, who...orders him to become her slave?!"--