Two people separated by time and space must unravel their tangled history before the world comes to an end.

Gekkan Mousou Kagaku is set in Most City in an unknown country in a small publishing house that prints a monthly magazine about the most outlandish of things. Everything changes when the staff of the magazine, editor-in-chief Tarou, his assistant Jirou and dog Saburou, meet with scientist Gorou Satou...

As Eishin Kuga—nicknamed "Mad Dog" for his unmistakable bloodlust—beats up his underlings, Yashiro watches and waits for his longtime friend to subdue him. Kanji Kageyama, an underground doctor, at last meets the young hothead whom Yashiro wants to recruit for his yakuza group. However, in light of Kuga's aversion toward Yashiro, Kageyama is ultimately left with the chore of temporarily housing him. But as Kageyama continues to insist that he has no interest in men, Kuga's shirtless presence, riotous attitude, and ceaseless teasing might just change his mind.

When college student Keiichi Morisato dials the wrong number while ordering for some food at his dormitory, he accidentally gets connected to the Goddess Hotline and a beautiful goddess named Belldandy appears out of a mirror in front of him. After getting kicked out of the dorm, Keiichi and Belldandy move to an old shrine and soon afterwards, Belldandy's sisters Urd and Skuld move in.