Hell Teacher: Jigoku Sensei Nube S01 E23 Requiem for a Promise

"Can you protect them all?"

When Hiroshi and his friends find a love letter addressed to Nube, their curiosity gets the better of them, and they secretly follow him to his date. Arriving at a seaside park, they see Nube with a cute girl and learn she is a former student of his. However, something about this girl does not seem quite right.