Gugu is a kid from Takunaha who currently works at Booze Man's shop. He and his older brother Shin grew up moving between different families as servants, which meant a lot of instability early on. When Gugu was really young, he got attached to one family and was genuinely confused when they left without him and Shin—he didn't fully understand what was happening.
At some point the brothers made a pact: they'd both work hard, save up, and eventually build a house of their own. It's basically their shared dream and motivation.
Content compiled by AnimeList.moe from publicly available sources.
