Associate Professor Akira Takatsuki's Conjecture, Vol. 4 (light novel)

The Enigmatic Professor: Volume 4 - Whispers of Yesterday

Spring unfolds as Naoya embarks on his second year, much to Professor Takatsuki’s joy. He eagerly resumes his role as the professor’s assistant, diving headfirst into a new wave of intriguing cases.

This time, they’re faced with a peculiar series of events plaguing an architectural office, each eerily connected to the number four. A sensational claim of a real-life mermaid sighting sweeps through a weekly magazine, ca…