For reason the father kicked the mother when the son was very young.
The son (Takuma) is living alone, a older woman become his neighbor Fuyumi, she take care off him(wake up, makes breakfast, school lunch, dinner) he called her Fuyumi-san, she called him Ta-kun. She is a bit teaser, one day she was drying her hair when topless in living room p.11.
Next day when he come back from school saw her sleeping he sucked her tits p.14, she pretend stills sleeping then at bath time she get in with him then hand shake his dick. p.18
Next day he can't hold it pushed her down, licked her p.22 then fucked her p.26, she begged him to cum out side, he did cum outside. p.29
2 options "Make mother toy" "Spoils mother"
"Make mother toy" son hate it when mother is such a teaser when he kind of suffer because he doesn't have mother. Next day when she wake him up he force her sucks his dick to repent for all those teasing and keep she is his mother secret. p.30 He fucked her at school. p.34 Another day he double hole her when she ready to make meal. p.39 He fucked her full, he want serious relationship with her, done with repent sex. p.45
Few month later he meet his father, said he is drop out of school to work, doesn't say he meet his mother, father didn't like that but didn't really stop him. He changes apartment, living with his mother who is pregnant. p.50 Mother still sometime teasing called him Ta-kun but mainly use Ta-san most of the time now. He called her both "mom" or Fuyumi-san
"Spoils mother" Next day, sucks mom tits while she shakes his dick. p53 Evening massage mom shoulder then fucks mom from the back. p56 Bath time, son and mom fucks. p.2
One day going out with mother, a male kid greet mom, mom kindly greeted back, when went near a park son pushed mom down for tits fuck, mom confused at first but guess son was mad/jealous because she greeted the other male kid. p.62
Some time later son meet father said he meet his mother and want to live with her, father locked son up, but after some days he released him, he gave up, son is basically disown from family. Son lives with his mother, fucks her full of cum everyday. p.6
@ Comrade Claus of course, cause in first time he fucked her when he ready to cum she begged him not to cum in her cause she is his mother, that's why after that the options are "Make mother toy" or "Spoils mother"