@Random-Rambling
She’s a weird case. You tend to attribute more upbeat or passionate personalities to tomboys, and Kobayashi is not just the opposite, but i could argue an extreme of sorts.
By an extremely technical definition, I would say she counts.
My first real girlfriend in high school was a tomboy but also had these big firm breasts which were pretty noticeable even though she liked to wear fairly loose-fitting clothes. We only went out for like three months and she took my virginity (I’d gotten a bj once from another girl a few months before that but no actual sex).