These two are Koba's parents and are pretty bad as him,

Domoto (49, M) Is a big-time CEO of a company that specializes in Mobility aid for extremely overweight people, such as compression suits and hoverchairs. He's pretty strict, and usually looks down at his son for what he has become.
Back when Koba was a teenager (17-18 years, along with being around 250 lbs during that time) Domoto would have to bribe his teachers to let his son pass tests with good scores, however one day, he forgot to bribe a maths teacher for an important exam, Koba failed it and dropped out of school, despite it being his fault for not bribing that teacher, Domoto still blames his son for not passing.

Asaka (46, F) Is the mother of Koba, always caring, but extremely relaxed, letting do Koba what he wants. She's the one with Japanese heritage (Domoto is also part Japanese, but from a different bloodline) and married her-now husband for the money, but soon had feelings for the latter and the two started a family together.
When she heard about her son's recent dropout, a huge feast was order all for him, this one-time "feast" however, started to be done more often than not and ballooning Koba's weight up to nearly 600 lbs by 19. Asaka would regularly shower her son in gifts, new high-tech and things of the sort, eventually leading to her giving Koba the compression suit on his 21 birthday.