ANIME Tachibanakan Triangle Information

When Natsuno Hanabi went back to her hometown to study in high school, she thought that she will have a new wonderful life. But Tachibanakan, the dormitory she was going to live in, was not what she expected.

When aliens suddenly invade the world, Earth seems to be fighting a losing battle until Arikawa, one of the defense command staff, accidentally discovers a young man lying on a hill. Tests soon prove the impossible: this one teenager, Kakashi, has the power to defeat the attackers! Unfortunately, Kakashi has also lost his memory, and with it the knowledge of how to actually use his power. Moving Kakashi in with himself and his own commander, Shiro, Arikawa accidentally starts a strange triangle of emotions and relationships. A triangle that threatens the fate of the planet as Kakashi begins to question his own motivations!

Makoto Ito rides the train to and from school every day. However, at the beginning of his second term, he falls in love with a beautiful girl that also rides the train. Unfortunately, she barely knows of his existence. Her name is Kotonoha Katsura, and though they attend the same school, they are not in the same class. In an attempt to catch her eye, Makoto enlists the aid of a close female friend of his: Sekai Saionji. She helps him, despite the fact that she--unbeknownst to Makoto--is in love with him. Thus the three are bound in a love triangle of life changing proportions.

A Keio University (one of the top three colleges in Japan) exam candidate, Touma Inaba, is interupted when a cute young girl, Urara Kasuga, arrives at his hotel room door. She later turns out to be his cousin who he barely remembers from his childhood. Urara, who had felt something special for him (an other-than-cousinly-love), invites Touma to live with her since he has no place to stay other than the hotel room. Before taking the test, Touma meets Meiko Yotsuba, a beautiful, sophisticated woman also trying to get into Keio. Meiko gets into Keio but Touma does not, due to a cold Urara had given him shortly before. Although he did not make it, he pretends he does to earn the respect of Meiko. Touma is caught up in a love triangle with Urara and Meiko, while struggling to keep Meiko believing he's really a Keio student and still be there for Urara at the same time.

The anime revolves around two protagonists, Hirono Hiro and Asou Renji. On Christmas Eve, Hirono Hiro meets a girl named Miyamura Miyako who was chasing a purse snatcher. Hiro later finds out that Miyako also goes to the same school as he does and they start hanging out together. This made Hiro's childhood friend, Shindou Kei, feel left out. Kei then tries to compete with Miyako for Hiro's affection and a love triangle ensues. The anime also tells the story of Asou Renji. Renji meets a girl named Shindou Chihiro at an abandoned train station. He soon learns that Chihiro suffers from a type of amnesia where her memory span only lasts for 13 hours. He also discovers Chihiro's dream of writing a novel, but she has never been able to fulfill that dream due to her condition. Renji then decides to help her fulfill that dream.