Takeru has been telling Ryou what ideal woman would be like, when suddenly a bright light zooms down out of the sky, hits a tree, and BAM! Who should appear in the tree but Takeru's ideal woman, naked as a jaybird? She seems very vulnerable and scared and obviously doesn't know the basics of human customs or even speech. Takeru gives her a name and vows to protect her.

Takeru and Hikari explain to his friends and family what happened the previous night. Hikari tells them she came to Earth from outer space because she was lonely, but doesn't know anything else about herself. However, because Takeru saved her he's now very precious to her. Takeru's male classmates go wild with jealousy because he's got a cute babe now.

Ryou is waiting to meet someone, although he himself doesn't really know this until he meets her. Her name is Akari, and she is obviously similar to Hikari in that she doesn't remember her past or have a name. Akari is living in the forest, because she remembers being there when she saw a night where there was a very bright light, and she wants to see a night like that again. Ryou begins going to see her regularly on his walks home, and begins to feel very protective towards her.

Ryou takes Akari home with him and soon his little sister Kimi starts to grow fond of Akari in spite of herself, and the three wind up declaring themselves a family, after which Akari moves into the Ninomiya household. Akari is introduced to Hikari and learns that she too came from space. Jennifer suggests that they used to be one being with no body, and then divided into two and gained bodies after they got to Earth.

Hikaru transfers to Takeru's school thinking it will be fun. During an emergency drill, she turns into her other personality and destroys part of the building to get at a blue crystal. Later she doesn't seem to remember what she's done, but it turns out the blue crystal is Ioneous, a robot-looking dude who refers to her as his "master."

It's summer break, and they all go to the mountains to camp. Hikari and Akari learn about nature and are happy; Ioneous and Jennifer get drunk, and are also happy. The group decides to play a game in the dark where they're basically supposed to split up into pairs and stake a flag on a rock. Hikari and Takeru wind up together and the rest of the group has fun spying on them, until Ioneous in monster-form starts running around in a drunken fit, making them think they're being attacked.