Half a year ago, a giant spiderweb appeared across the sky. It received significant media attention for a time. Eventually, as nothing seemed to be happening, people returned to their normal lives, ignoring the spiderweb. Amedome Tsutsuji lives his daily life beneath it. At school, he has been nicknamed "Ninja" because it is so easy to overlook him. Even automatic doors fail to acknowledge his presence by opening. However, he can see what others cannot: aliens are descending from the spiderweb, taking human bodies as hosts, and eating people. For this reason, he uses his ninja-like ability to carefully guard his crush, Mizuno, as she heads home from school. In other words, he stalks her, but with the best of intentions. He is determined to be there to protect her when the spider-aliens attack. To that end, he teams up with another, friendlier alien named Tsuda, who gives him a powerful weapon: a faucet. Will Tsutsuji be able to protect Mizuno from the parasitic spider-aliens with his trusty faucet?