welcome to Yande!

Chara design is absolutely beautiful !

Maybe it's a better idea to change the rating?

It's not that "Safe"

Not safe? It's a swimsuit, it is safe.
Not to mention she is 16 years old canonically, and not even very short.

No, it's questionable due to the camel-toe. Unless you can show me her birth certificate, then I will have to assume it's based off a pre-pubescent girl, and get's the loli tag.

spoilerloli is subjective

Calm your tits, she basically has a birth certificate as she has official height, age and measurements, being 154cm and 15 or 16 years old (can't remember), but whatever it's your call, as with calling it questionable or safe (though it's really so subtle that you won't find any swimsuits in real life showing less)
Just please don't go full Australia and call every girl with small breasts a loli.
And the bra and pantsu tags are still not right, as it's clearly a bikini.

As I said, the loli tag has always been subjective, but the image is questionable. If in doubt, always err on the side of caution.

That's why I said it's up to you to take the measure you deem right, but don't completely write off what I'm saying as if I was talking out of my ass.
Love Live girls have all the proper measurements, basically their "birth certificate" available for them. The breasts on the picture are also solid C cups (they're even too big for what they're supposed to be, since they should be flat in that position, instead of having that visible volume).
And about the image being questionable, I guess I just don't have perverted enough eyes to see it as such. :)

Talk about leaping to assumptions.