It's cute. The whole age stuff bug me really hard but it's cute. Oh, well, at least it's more like a innocent crush a young boy have on an older lady, it's not like it's the other way around (it would have been a big nono situation).
I'm really curious to see how it will plays out. I think even when our dear shota will became an adult, Kazu won't see him as anything more than that "strange but nice child".... At first, at least. ( ͡° ͜ʖ ͡°)