Engage Kiss

Miaka, a junior high school student in Tokyo, has normal problems: fights with her mom, entrance exams, and deciding where she's going to go eat with her friends. But when she finds a mysterious book in the library, her life is changed forever when she and her best friend are transported inside!

The skilled hunter Kikuru Madan has decided to retire out of fear of wasting his youth. One day, a guild staff member suggests that he go on a quest with a new female martial artist named Hitamu Kyan. However, she keeps getting hit by monsters one after another.

One day, humanity was invaded by another world. Having experienced that battle, known as Other World War I, humanity moved to marine floats, built for emergency evacuation purposes, as soon as Other World War II began. It's around that time that Kizuna Hida is summoned by his elder sister and visits the Strategic Defense Academy Ataraxia where he meets Aine Chidorigafuchi, a girl who uses Heart Hybrid Gear Zeros to fight the otherworldly enemies. He has a tough time dealing with her, but when her Gear runs out of energy, the only way to get it back in action is to do something lewd to her!

The story is set in a world embroiled by war between Humans and Demons. The Humans’ greatest hero invades the Demon Queen’s castle determined to vanquish her. However, instead of fighting back, the Queen proposes an alliance with the Hero. She explains how a sudden end to the war can bring further chaos to the world as the Humans once united to stand against their common enemies would eventually begin fighting among themselves, with similar issues already occurring at the Demon Realm. Convinced by her words, the Hero joins forces with the Queen and together they execute a plan to bring prosperity and a lasting peace to both Humans and Demons alike.