When Nube and his class arrive at a small island to carry out beach activities, they heard a forbodding tale from an old man residing on the island. Legend has it that there is a creature known as the sea spider in the open seas around the island. When the creature is past 200 years old, it will turn into a monster and devour humans to satisfy its appetite. However, curiousity kills the cat and Yukime decides to pursue the authenticity of the legend. And then, a girl suddenly appears on the beach. Possessed with a strange charm, she immediately attracts Hiroshi's attention and overcomes him. Soon later, strange things start to happen to the others whereby Kyoko and Ritsuko-sensei got attacked under strange circumstances. The true identity behind the mysterious girl is questioned and the legend behind the sea creature seems to be true after all.

The gag manga depicts the everyday life of the demon Memumemu-chan, who appears before the high school student Hyouta one day. She's come to seduce men and steal their souls, however, has neither the motivation nor the ability to carry out her duty. The story revolves around Memumemu, Hyouta, who is often misunderstood as a lolicon due to Memumemu, and the super sexy mother-daughter duo who manages the apartment Hyouta resides in.

Third season of .