Kanenone Gakuen is an all-male boarding school located in the countryside of Japan. Although an all-male school is nothing new, life can become quite difficult when there are no female students for miles around. In order to help the psychological health of everyone involved, the school board has decided to try and merge with the nearest all-girl boarding school in order to become co-ed. The boys of Kanenone are more than thrilled at the prospect, and the girls are curious as to how interesting school life might become if there were more boys around. Before any serious decisions are made, the girls have been invited to stay at Kanenone for one month as a test. Green Green follows Yuusuke Takazaki and his naughty room mates called the Baka (Idiot) Trio, and their ability to talk to the girls without making complete fools of themselves. But as soon as the school bus with the girls arrives, things become weird, hormonal, and hysterical. In particular, a girl named Midori Chitose leaps off the bus and immediately embraces a very confused Yuusuke. Is he a natural ladies' man, or do the two of them have a shared history that he is not aware of?

During a monster attack on the city, which is something that happens quite often, Silk and her two friends try get close to the attacking monster for a better view. An unfortunate choice of location to watch from leads to UFO-man, the city's giant protector, to land on the girls crushing them to death. Feeling sorry, UFO-man blames their death on the monster and promises to bring Silk and her friends back to life by lending them his power but the catch is that they now have to become the city's protector as well. (Source: ANN)

Yuto Takamine and his younger sister-in-law Kaori, were at their parents' grave, when they were suddenly summoned into another world, Phantasmagoria. The King and a woman named Restina took Kaori as a hostage, and ordered Yuto to fight against their enemies. Then, the King gave him a sword called Motomeh to protect their kingdom from enemy spirits. Kaori will only be freed if Yuto helps protect Phantasmagoria. Thus, Yuto's journey begins... (Source: ANN)

Spring is coming and the all-male Kanenone Gakuen prepares to become coeducational with the new academic year. Naturally, the teenage boys are more than thrilled at the prospect of having adolescent girls around. With only a few months until the merger, the incoming female students decide to pay a visit to the academy. As luck would have it, Yusuke Takasaki gets a chance to confess his feelings to one of the arrivals, Futaba Kutsuki, who is also looking forward to the encounter. However, as the pair struggles to find a moment for themselves, a girl called Midori Chitose visits them in their dreams, urging them to do their best and encouraging them to seize the opportunity. From then on, the lovers decide to make the most of their short time together before they are separated again. [Written by MAL Rewrite]