13 and 16, thats not "too" bad.
You can think of it like this. When Honoka is a first year High Schooler, Tanimoto is going to be a 3rd year.
I think its obvious that the author is intent on making Tanimoto, Kenichi's brother-in-law in the future, lol. Besides, if Kenichi's mom is of any indication, Honoka is gonna be hot when she gets older.
