Chapter 206

"Let you down" is the ninth chapter of the 23rd volume and the 206th chapter overall of the Tokyo卍Revengers manga series, written and illustrated by Ken Wakui. It is also labeled as one of the two side stories in the 23rd volume, majority of which is a flashback from Yasuhiro Muto's perspective.

Summary
The scene opens with Mucho swearing loyalty to Mikey as the 5th Division 'special duty' captain. That night, his division is appointed Sanzu, a troublesome middle-schooler whom Mucho finds much of himself in. Over shogi, the two discuss Baji, whose problematic nature has grown suspicious. Sanzu plays a defensive opening in their game; when prompted, he explains that 'protecting the king is priority,' which was why he took on Yotsuya Gang alone for dissing Toman. Mucho advises Sanzu to put his own safety first, gifting him a mask to cover his scars. Sanzu happily accepts.

Over the span of six months, Sanzu gains Mucho's trust and brotherhood with his unwavering fidelity, effectively becoming his second-in-command. During the interrogation of Kokonoi, Inui, and Takemichi, the latter asks Mucho if he is betraying Mikey, to which Mucho replies grimly, 'It would have been different if I'd met him first.' Later that evening, Mucho informs Sanzu he will be withdrawing from Toman, but Sanzu affirms his faithfulness to him.

Half a year later, Mucho leaves juvenile detention, finding Sanzu waiting in congratulation. The latter takes him to the third wharf where the Kanto Incident occurred, and promptly slashes his torso with katana. Taking off his mask, Sanzu references that day playing shogi, accusing Mucho of treason to Mikey. As he deals the finishing blow, Mucho tears up, wondering if 'this is the price for betrayal...' In 2008, a news broadcast reports of skeletal remains found near the Tokyo Bay Area, with Sanzu watching from the city walk below.