Yukako Yamagishi Falls in Love, Part 9 (山岸由花子は恋をする その⑨ Yamagishi Yukako wa Koi o Suru Sono 9), originally Echoes Cliff (エコーズ・クリフ Ekōzu Kurifu) in the WSJ release, is the thirty-seventh chapter of Diamond is Unbreakable and the three hundred second chapter of the JoJo's Bizarre Adventure manga.
Koichi, victorious, walks toward Yukako to check on her as he is still worried that she might have died. He sends Echoes toward her and sees that Yukako is now unconscious and has white hair, but is otherwise fine. She suddenly wakes up and grabs Echoes with her hair, also cutting off its tail which falls down the cliff. Yukako cannot forgive Koichi for damaging her hair and tries to kill him via Echoes, but the cliff crumbles around her and she falls down. She doesn't have time to grab anything else and is almost impaled on the pointy rocks below, but instead bounces back up the cliff. Echoes has planted the sound "boing" on the rocks to save her, and Yukako is unharmed. As Koichi unceremoniously departs, Yukako understands that he still thought about saving her despite her murder attempt, and falls back in love as a more confident Koichi meets his friends Josuke and Okuyasu and opts to leave her alone.
Incidentally, a drunk fisherman has witnessed Yukako bouncing on the rocks and the newly named Boing-boing Cape becomes a local landmark.
Some time later, Koichi is given another English note, having this time scored a perfect grade. He feels unsure about what to feel about this.