Enigma Boy, Part 2 (エニグマの少年 その② Eniguma no Shōnen Sono 2?), originally A Sign of Terror! (恐怖のサイン！ Kyōfu no Sain!) in the WSJ release, is the four hundred fifth chapter of the JoJo's Bizarre Adventure manga. It is also the one hundred fortieth chapter of Diamond Is Unbreakable.
Although Josuke is glad that his mom is only unconscious instead of being hurt, he's extremely angry that the enemy resorted to a dirty trick instead of dealing with him directly. Josuke asks Yuya where the enemy went, but Yuya only knows that he's somewhere nearby.
Meanwhile, Terunosuke is surprised that Josuke used Yuya to help him, but he thinks it's fine because he intended to get caught eventually. He dragged Tomoko into the situation on purpose, knowing that it would agitate Josuke. Terunosuke plans to observe Josuke to discover what he does when he's afraid.
One hour ago, Tomoko entered her house and felt a sense of uneasiness. She asked if Josuke was home but got no response. After she opened the fridge, she blamed Josuke for eating one of her snacks and taking a bite out of another one. When she was about to leave the kitchen, she noticed a hot coffee on the table. In front of it was her panties folded, explicitly labeled "Your Panties".
Terunosuke spoke up behind Tomoko, which frightened her into pulling a knife and threatened him to leave her house. Terunosuke unfolded a paper and one of Tomoko's snacks and a cup of hot coffee came out of it. While menacingly licking Tomoko's snack, he tells her that her reflexive sign of fear is gulping. Tomoko attempts to run away but Enigma attacks her and she gets trapped inside paper.
Back in the present, Terunosuke says that it was easy to capture Koichi, as his sign of fear was blinking twice. Terunosuke then realizes that when Josuke's afraid, he bites his lower lip. Yuya is confused as to how Koichi's scent is coming from Tomoko's pocket, but doesn't plan on getting any closer because he doesn't want to take any chances.