Waiting in that Summer

When a group of friends decide to make a movie over a long summer holiday, they end up learning a little about filmmaking and a lot more about each other and themselves. What begins as a simple way to avoid the summer doldrums quickly turns into something much more complex, intimate and revealing, as the maturing relationships between the members of the young cast take on new, and sometimes very unexpected, turns. (Source: Sentai Filmworks)

Kusanagi Kei, a high-school student living with his aunt and uncle, has an encounter with a female alien. This alien is revealed to be a new teacher at his school. Later, he is forced to marry this alien to preserve her secrets. From there, various romantically-inclined problems crop up repeatedly. (Source: Anime News Network) *Note: \-The title was never "- sensei," the Japanese characters phonetically spell "teacher". \-The chapter count includes one extra chapter.*

Maiku Kamishiro has a problem. Actually, make that two problems. He has two young girls boarding at his house, each claiming that they're his long-lost twin sister! Which one is Maiku's sister? Which one is a total stranger?