Okuhara Jin was about to confess to his childhood friend when they were suddenly transported to another world. The location they were in happened to be filled with tentacle monsters and Jin was eaten by a large tentacle monster. When he regained conciousness, he discovered that he was now in the body of a small tentacle monster that was spat out by the large tentacle monster that ate him earlier. Jin discovers that his new tentacle body causes him to periodically lose control and attack females with his tentacles. He now tries to discover the mystery of the hole they were in, dubbed "Tentacle Hole", together with the group of explorers who rescued his childhood friend.