If you're looking for manga similar to Please Twins: The Summer Never Ends, you might like these titles.
Kamishiro Tomoki is an Otaku who is studying for college. One day, he received an outrageous "package" from his father: 9 year old blond girls who are his dad's illegitimate children from one of his business trips...... The twins, Selly and Riru are completely spoiled and drives Tomoki crazy. Not only that, the sisters have a "secret" plan to kick out Tomoki and claim the house just for themselves. Will Tomoki manage to make peace with the girls?
Yamato loves his little sister. His sister is the cutest and sweetest girl in the world, and he won't settle for second best. Unfortunately, everyday life and the rest of the world intrude on his idyllic plans, and he finds it's not as simple as he imagines it should be. Follow along with tough Yamato and cute Masaki as they deal with the problems of an otherwise normal family life.
Three 20-something sisters, Ayame, Kaede and Sumomo, have just about had it with men. Ayame walked in on her husband's infidelity, only to have him leave her for the other woman. Kaede had a crush on a colleague, only to find out he was sleeping with his high school students and keeping a porn stash of their pictures. Sumomo just can't seem to find a guy that's good enough for her. Their lives change the day their little brother Mikio comes to Tokyo to live with them, just after high school graduation. They all become immediately infatuated and aggressively sexual with him. Mikio wishes they would just act like normal sisters.
Imagine a country where couples are chosen based on the compatibility of their genes. Whenever a resident reaches the age of 14, a partner will be suggested to him or her based on which match would result in the best child being born.
Azuma Sakuragi is deeply in love... with his twin brother, Miyabi! Miyabi is a pure genius at archery, but pretty much useless at everything else. You would think Azuma would be fed up with taking care of him all the time, but instead, he's happy to spend as much time with Miyabi as he can... until one day, the A.C. in Miyabi's room breaks down, and Miyabi has to sleep in Azuma's room... and share his bed! Can Azuma keep himself from secretly touching his brother?
Shinichi has been going to his uncle Chiharu's house since he was a child to play his favorite game of chess, but one day he realizes another feeling deep in his heart. He challenges Chiharu to a game of chess just to tell him how he feels, but...