The famous k-pop idol V from BTS isn’t called V in Japan. Actually, he’s called TaeTae.
It is difficult pronounce the letter ‘V’ in Japanese, so they started to call him “TaeTae” because his real name is Kim Tae Hyung. And TaeTae was his nickname on High School.
As a curious fact, in a Japanese show the interviewer asked a married couple to write the favorite thing of the wife. She wrote bread, but his husband wrote “BTS Tae Tae”
https://twitter.com/verykth/status/1211310484277911554
TaeTae is the unofficial name for V, but he introduces himself as TaeTae too. Just like Jungkook, that introduces himself as Guku (because the last part of his name is pronounced like “Jung-Guku” in Japan)
