@Shtoops
Depends. For the older woman, I'd assume she was either in her mid-to-late twenties ( mainly based on these female corporate characters usually being like 27 or 28), and no less than 24 (probably after college).
As for the younger one, since she's in high school and doesn't seem to be completely preoccupied with college, she's probably a 1st or 2nd grade highschooler- so 17-18 years old (since asians usually consider someone 1 year old when they're born)
So it's actually not illegal since I think the age of consent to date any age is 16 in Japan (as well as some places in America too)