The Yuzuki Family’s Four Sons

Both are homey dramas with adorable kids and fathers/father figure of the family solely tending to children.

If you liked Kotaro, I bet you would love the Yuzuki brothers! Similarly, children from those dramas had 'lost' their family at a young age and the drama revolves around the relationships they had formed. This is what I search for a slice of life family dramat but both offers extra cuteness since the main cast are these children who are really great in acting for such a young age. I would often break a tear but the over-all atmosphere of these two dramas is warmth (and cute).

Japan recently introduced a lot of series around male families only, be it 1 or 2 generations, not bl - just ordinary single parent/sibling.
Four brothers - speaks for itself - daily routine and hilarious situations of four brothers, the youngest being 5-7 yo , the eldest - supports family
Lion - similar plot, oldest brother support autistic younger brother, then Lion jumps into their life, destroying order and wreaking cute chaos.

Both are set in a school setting
Both have many cute child actors
Both are emotionally heartwarming watches that give the same kind of warm fuzzy feeling