Hell Teacher Nube: Summer Holiday of Fear! Legend of the Sea of Suspicion

Nube's class visits a small island for their summer break, where they hear a local legend from an elderly resident about a sea creature known as the sea spider. According to the legend, once the creature reaches 200 years of age, it transforms into a monster that devours humans. Yukime becomes intrigued by the story and decides to investigate, while a girl with a strange aura suddenly appears, causing Hiroshi to become infatuated. As the trip progresses, strange occurrences start to happen, including Kyoko and Ritsuko-sensei being attacked under unclear circumstances, leading to questions about the mysterious girl's identity and the validity of the sea spider legend.