Natsuo's Love Beach (2010)

Bad at sports, Takeshi and Ryo, a gay couple, get together with Akira and Mitsuo, another gay couple, to participate in a beach volleyball tournament all the while Ryo is set to meet a man he met on a dating site. As the tension grows, Takeshi's older sister, Rika, shows up with her lover, Yuichi, who was the captain of the volleyball club in high school.