If you're looking for manga similar to Megalo Box 2: Nomad, you might like these titles.
Riku experienced a lot of pain and tragedy in his early life. After his father's death, a former-boxer Yakuza man taught him how to do a basic punch, and that punch saved his life when he had to defend himself from his mom's drug dealer. He ended up taking the drug dealer's life, marking him as a killer. Criminals continued to come after him, leading to more tragedy for the people who attempted to care for him. All of this drove him to ask that same former boxer to teach him to become stronger, which led him to a rundown gym, his door to the world of pro boxing!
Two boys who would never have been able to meet each other under normal circumstances will now carve their mark in boxing history!
At the end of Ring ni Kakero 1, Ryuji Takane went up against "Superstar" Jun Kenzaki for the World Title. Now, 17 years later, Rindo Kenzaki, the son of Jun Kenzaki and nephew of Ryuji Takane, lives with Ishimatsu Katori, the "Kenka Champion" from Ryuji and Jun's time. Rindo will meet up with a new generation of boxers to create a new Golden Japan Jr. to take on the world.
Hiroshi Suzuki is just a normal student. He was born as an ordinary person and will die as an ordinary person. Until one day when he met Aika Tenno...
In the 19th century empire after the war, rose "mechanical boxing" which involved people who had had their bodies modified. Under his uncle's tutelage, Levius, a lonely youth who lost his father in the war and whose mother is in a coma, enters the mechanical boxing scene...