Right. Time to wear my tinfoil hat and get some deductions on the ground.
First, Ms. Konno is obviously not Yuuta's blood mother. Some people think she is Ren in disguise in the previous chapter's comment thread, but I believe Ms. Konno isn't Ren even if she is related to Ren.
The repeated mention of makeup already tells us Ms. Konno most probably hides her age lines. In combination with her calling Yuuta's father "little Takeh", it makes me think "little Takeh" is her actual son while Yuuta is her grandson. No idea why she can't take care of Yuuta as his grandmother in this case, but it's probably has something to do with how she is also hiding her real face (thus her real age).
Currently I wanna say "little Takeh" is Ren and thus Yuuta is Ren and Yuki's son, but the timeline kinda doesn't fit given in the 1st case Ren's last update was 1.5 years ago while in this 2nd case "little Takeh" is mentioned to have been dead for 3 years. Also if next year Yuuta is entering elementary school, then that means he is currently around 5 to 6 years old depending on his birthdate. So if Yuuta is actually Ren's son, there would have been around 4 years of timeskip between case 1 and this, quite a lot. There is a chance that there is actually a timeskip, but I will wait until we get more facts.