Many years ago, a girl told Keitaro that according to legend, people who attend Tokyo University are destined to fall in love and live happily ever after. That's why he promised a childhood friend that when they grew up, they would both attend Tokyo U., but now he's struggling to get into this prestigious institution.

His parents, no longer able to support him after failing the entrance exams twice, suggest he go stay with his grandmother Hina, who runs a hotel and is about to retire, so the place requires a new manager. Once there, the old lady is nowhere to be seen, so Keitaro takes advantage of the hot springs facilities. As he relaxes in the soothing water, however, a young woman enters the baths and is horrified to see a man there. It turns out it is no longer a public hotel and has been converted into women's only apartments! Now, they must try to get along all while Keitaro tries his best to pass the entrance exams and recall the lost face of his childhood friend.

Similar to Green Green, Love Hina is the story of someone trying to reunite with a person from their past, while adjusting to domestic life with a group belonging to the opposite sex.

When Maiku Kamishiro's adoptive parents pass away, he is forced to support himself. The only clue about his past is a photograph: two small children, a boy and a girl, playing in a pool together in front of a house. Now an adult, he saves up enough money to afford to live at his former home. One day, a girl with the same deep blue eyes as he shows up on his doorstep, claiming to be his long-lost twin sister.

In possession of the same photograph as her only proof, she introduces herself as Mina, begging Mike to allow her to live in her former childhood home. As they bicker back and forth, there is another knock at the door. Yet another girl with the same color eyes, claiming to be Maiku's long-lost twin sister! Which girl is telling the truth, and which girl is just a stranger?

This anime is similar to Green Green as it is about reuniting with someone from the past, with the male character having to adapt to all these females that keep showing up in his life. It's a series that focuses more on family reunion this time, rather than a romantic one.

Shouta attends a class reunion where a bunch of his former classmates all have successful careers. Being the only one who hasn't really accomplished anything in his life, they mock him for it. While he goes outside for a cigarette break, he accidentally falls into the pool... what somehow makes him travel back in time to his school days! The successful women who made fun of him are back to being his young classmates. This time around, however, his perverted adult brain is having a hard time coping with all the erotic imagery during such innocent activities like gym classes, swimming, water balloon fights, or playing doctor.

Similar to Green Green, this series focuses on a relationship from the past. This time around, though, the reunion actually ends up taking place in the past! No one ever said time travel was simple...

Five male students have been invited to attend a formerly all-girls' school, and all five of them are completely socially inept when it comes to actually speak to girls, however. One day, one of the new male students accidentally drops his sumo wrestling-themed eraser near one of the girls, Chiyo. Excited that someone is into sumo wrestling as much as she is, Chiyo and Kiyoshi end up talking the whole afternoon.

Unable to believe his luck at actually succeeding in talking to a girl, Kiyoshi wasn't paying attention while his fellow male students concocted a plan to peep on the girls taking a bath. The punishment for being caught? All five of them get sentenced by the school's underground student council to spend one month in the school's on-campus prison.

Much like Green Green, Prison School is a hilarious comedy anime about a newly co-ed school starring a cast of horny guys, and both feature main characters that aren't all that interested in being as perverted as their friends.

When Shingo gets a phone call from his younger sister saying that she's lost, he sets out to try and find her. Unfortunately, due to Sakuno's terrible sense of direction and dying phone battery, Shingo is only able to narrow her location down to the Old District. Meanwhile, Sakuno finds a tree to shelter herself from the rain, and as she waits for her big brother to find her, a friendly girl walking past offers to share her umbrella. Her name is Airi, and she got lost too!

The reason Sakuno got lost in the first place is that their co-ed school is being merged with an all girl's academy as part of a trial run, so she wanted to buy ingredients for a special lunch for their first day. Shingo, Sakuno, and a handful of mostly male students are being integrated due to the lack of funds at their old school, but some of the female students and staff are not happy about this sudden change. The most vocal person being the siblings' new friend, Airi!

Mashiro-iro Symphony is similar to Green Green as both stories involve formerly single-sex schools becoming co-ed as part of a trial run. Also, they both feature a colorful cast, with comedic elements thrown into a story about romance.

Fudo Nomura, a new transfer student, joins a formerly all-girls' school as punishment for getting kicked out of several other academies. This is where delinquents get sent to have their behavior corrected, but shortly after, the school became co-ed, and the male students would often leer and harass the girls. So, a new rule was implemented: from then on, all female students are allowed to carry weapons on school grounds! Soon enough, an elite group of sword-wielding students rose among the ranks as a disciplinary task force.

Now, the male students are too terrified of the girls and try to pass themselves off as girls so they'll be left alone. Nomura, however, takes issue with this and refuses to conform, attracting the wrath of the leader of the Supreme Five Swords, who immediately makes it her life's mission to correct his attitude.

Like Green Green, this is another anime featuring a single-sex school adapting to becoming co-ed. With both shows featuring interesting characters, there's bound to be a favorite among them for any anime fan.