The following is IGN's guide to the substory Pocket Circuit Fighter! in Yakuza
Pocket Circuit Fighter, Yakuza Wiki
Yakuza Kiwami : Pocket Circuit Race - Kazuma Cup 4 & 5
Pocket Circuit Racing - Like a Dragon Gaiden: The Man Who Erased
Pocket Circuit Racing - Like a Dragon Gaiden: The Man Who Erased
Pocket Circuit Fighter, Yakuza Wiki
Yakuza 0: Best Pocket Circuit Fighter Race Builds
Yakuza 0 - Pocket Circuit Guide
Yakuza 0: Kamurocho Residents / Characters - TV Tropes
The Fighter's Crown - Yakuza 0 Guide - IGN
Yakuza 0: Best Pocket Circuit Fighter Race Builds
Yakuza 0 Friendship Guide