Bikini suit for a Japanese penpal?

I have a Japanese penpal who is turning 16 next month. Swimming is one of her hobbies. She's only 1.5m (4'11'') and 38kg (83lbs). I'm planning to buy her a kid's size 12 bikini suit that is not kiddish looking for her birthday. Do Japanese girls value swim suits?

That's a very individual thing. Not all women here are comfortable with wearing a bikini, and many don't like to go to the beach because they like to keep their skin as light as possible.

Bikinis here are more likely to have little skirts attached to them for modesty as well. The bra-top part also tends to be well padded.

Make sure first that it is something she will actually wear.

For a 16 year old girl, pools, beachs, bikinis and tanning are very common things. But of course, it totally depends on each person's preference.

i was told by my j-gf that it's a trend to keep the skin as pale as possible...while its the opposite over where i come from

Just for reference, this is a ranking list of swimsuits for girls.
http://ranking.rakuten.co.jp/rnk/navi/g409365/

Thank you very much for the suggestions... the link Uco provided is particularly helpful. I�fm planning to buy her a swimsuit or 2 from one of the most popular styles. Omg the swimsuit prices in Japan are insane! Now at the end of august, a lot of swimsuits are marked down 80% in the US. So buying a swimsuit her size costs under $5 (and quite a good brand too) here.

The models in that link look around 20 or so. I am guessing the younger set in Japan would prefer pastels and cuter designs?

She has 3 suits (a 1 pc, a bikini, a tankini). Considering she loves to swim, I think 3 is not enough so she's very likely going to be happy with more. I swim less than she does and I have 10. How many swimsuits does a Japanese teenage girl typically have?

Betty wrote;
So buying a swimsuit her size costs under $5 (and quite a good brand too) here.

The only down side I notice about U.S./European swimsuits is that a lot of them are made from very thin material, therefore allowing it to be somewhat transparent when wet. At least, a lot of them tend to make your nipples obvious. That is not so common in Japan, especially among young teens. But as long as the material is thick enough, or as long as you can apply pads that's fine. Also, not many young teens prefer to wear G-strings or the like.

The models in that link look around 20 or so. I am guessing the younger set in Japan would prefer pastels and cuter designs?

I found something that says, "These are popular among senior high school girls."
http://item.rakuten.co.jp/kasukawa/pz-538-3057/

How many swimsuits does a Japanese teenage girl typically have?

Well, I don't think a lot of high school girls can afford more than 2 or 3. Sure, parents might be able to afford them, but you don't want to spoil your precious children. My 17 year old boy only has one for the beach and another for school!

I am a very open minded liberal guy. I showered in the natural in high school, the (compulsory) army and, when I studied in Finland, I bathed naked with my host family and their guests as this was the local custom.
But I honestly believe that a bathing suit isn't a suitable gift to a friend, even one of the same sex..
It would really creep me out if my best buddy ever gave me a Speedo!!! It is bit too personal a gift, as each person has not only his/her own like/dislike but their bodies fit better in some clothes than others and friends shouldn't know all these private details.

My mom wouldn't have dared buying my dad's underwear and clothes nor him hers.
My brother and me started buying our own underwear and all our clothes from the age of 12 on. .

Monkey See,

I think there is a big difference between a guy giving a bathing suit to a guy and a girl giving a bikini to a 16 year old girl. I as a female wouldn't mind having a bikini as a gift from another female I've known for a while, unless it's a used one!

Anyway, the safest thing for the OP to do is to ask the receiver in advance.