The Akita's closest confirmed relative, where two independent lines of evidence agree, is the Chinese Shar Pei.
It is among the breeds nearest the Akita in the Sniff atlas genetics, which rests on 22 CanVAS Akitas, and a separate study of 161 breeds (Parker et al. 2017, Cell Reports) places it in the same branch of the dog family tree. The same study also places the Chow Chow on that branch. Sniff holds 17 Chow Chows, fewer than the 20 dogs a genetic comparison needs here, so it is not confirmed yet.
Breeds that only one of the two puts nearby are left out. A distance in one dataset can partly reflect which study genotyped the dogs, so a relative is named here only when an independent study agrees.