Well, its an sad news to all J-Pop fans, an legendary J-Pop boy group band Arashi annouced that they will go on hiatus by 31 December, 2020.

Here is the link on AramaJapan:

http://aramajapan.com/news/arashi-to-go-on-hiatus-in-2020/95027/

They'll start this at 31 December, 2020. So i guess 2020 Tokyo Olympics could be the last one thing they'll peform there as they we're selected by the Japan choice for the artists to peform.

(sorry for my poor English)

oh, I didn't knew about the performance for the Olympics. Can you tell me where you saw that news?

 SumiTheCat:

oh, I didn't knew about the performance for the Olympics. Can you tell me where you saw that news? 

Here you go!

https://aramajapan.com/news/ranking/2020-summer-olympics-opening-ceremony-performer-ranking/18584/

 Hotsushi-kun:

Here you go!

https://aramajapan.com/news/ranking/2020-summer-olympics-opening-ceremony-performer-ranking/18584/

Thanks for the link. 

that being said, it's quite an old article regarding this matter and it seems more like a poplular vote than any definite apointment. I guess the line-up is not settled yet. I'm looking forward to who will be in the ceremonies.