Ep. 4: Satoshi traps Daisuke in a cold room to test his theory that he is Dark.

Satoshi Hiwatari, a genius student at the same school as Daisuke, leads the investigation to capture Dark. Suspecting Daisuke is the culprit, Satoshi tests his theory after seeing Daisuke check his Alumnus Profile. He traps them both in a chilled storage room with a code lock that even Daisuke cannot break. When Daisuke resists Satoshi's pressure to reveal his identity, Satoshi loses his composure, causing Krad, Dark’s enemy and other self, to appear. Daisuke summons Dark, leading to a battle where neither side wins. Following the conflict, Satoshi decides to leave school for a while to distance himself from Daisuke.

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