Onee-shota Mujintou Seikatsu ~ Tanshou Houkei no Harem Tengoku [小さいの愛心]

Description:
Five people participating in a certain survival experience camp unexpectedly get stranded!! …However, since all of them are survival experts, they remain completely unfazed. When they realize they won’t be able to escape the island for a while, they casually start their survival life—
Up until now, the protagonist ‘Aki,’ who had been mistaken for a girl, has his true identity as a boy—and even his short, phimosis condition—completely exposed in front of the four older sisters. But to his surprise, it turns out the older sisters are perverts who absolutely love short and phimosis!!”