Company President Yonoi Tsukihiko and orange farm heiress Hanabata Mikan are still total opposites, but they're finally dating! Alas, their happy-ever-after seems elusive as Mikan comes crying to Tsukihiko one day to confess that Tsukihiko's cousin Seiya had tricked her into sleeping with him! Hot-headed Tsukihiko marches over to confront Seiya, but the very moment he opens his mouth, Seiya plants a big wet one on his lips! What exactly is the devilish Seiya up to? Find out in the fifth volume of Yonoi Tsukihiko's Happy Hell.