How to prevent your onii-chan from looking up other girls' skirts: 1. Be tsundere as fuck to assert dominance 2. Have sex with onii-chan 3. Repeat step 2 all day everyday 4. ??? 5. Profit
On spring break, Daisuke heads to a tropical island. Turns out, his female cousin and a couple of his girl friends are also there. What do you get when you put them all together with a bunch of teenage hormones? A harem. It's always a harem.