Diamond is Unbreakable - Chapter 24 
Toshikazu Hazamada (Surface), Part 1 (間田敏和(サーフィス) その① Hazamada Toshikazu (Sāfisu) Sono 1), originally The Mysterious Third-Year Student (謎の3年生 Nazo no 3-nensei) in the WSJ release, is the twenty-fourth chapter of Diamond is Unbreakable and the two hundred eighty-ninth chapter of the JoJo's Bizarre Adventure manga.
One day, Tamami meets Koichi and Josuke coming out of their high school. He tells them that he took up honest work as a debt collector and then gives them a tip about a possible Stand user. He presents a photograph of Toshikazu Hazamada, a fellow student in Josuke's highschool. He reveals that after a dispute with Hazamada, one student gouged out his own eye with a pen, an action the student claimed he didn't remember doing. Josuke decides to investigate Hazamada, and Koichi accompanies him, which inspires admiration in Tamami, who leaves soon after.
Josuke and Koichi inspect Hazamada's locker but do not see any trace of the Bow and Arrow. However, a strange human-sized mannequin is in the locker. The mannequin transforms into Josuke when he touches it, confirming that Hazamada is a Stand user.