When alien Princess Valkyrie crashes her spaceship into Japanese teenager Kazuto's bathhouse, she revives him by giving him half her soul with a kiss. But the act transforms her into an 8-year-old girl, and she's now dependent on Kazuto. In more outlandish adventures -- in outer space, no less -- the odd pair of soul mates set up shop on an asteroid, battle intergalactic pirates and face being split up by a Valhallan leader.