Gojo Satoru is staying at Suguru's for summer break. Now, Suguru and Satoru has been friends since childhood. So, they know each other's family members. What Suguru doesn't know is his best friend, Satoru's huge crush on his sister since kids. Yes, she is younger than the two. Gojo uses this summer break in an attempt to get closer to you since you all will be living under the same roof.