Japan #51 Kai is a modified version of Japan 51. Rather than aiming at helping track athletes, this version includes ingredients like black soy beans to help vision, as it is aimed at Nascar F-1 racers.

Kai really likes the name and reminds people when they forget the suffix because he feels like he lost to Kazuma but Kazuma said Kai inspired him to tailor the recipe to the racers.

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