One day we saw a Rin’ concert, I think the sakitama tour in 2004, and I saw it with Yuie, my BBF who plays the koto. They (Rin’), when having a pause between a piece and another, have to adjust tuning (especially koto), but in the concert we saw, they didn’t. Was it just that the record label cut the tuning moment or what?
Probably. They may not have included it in a DVD release, thinking that it isn’t such an interesting or important part of the performance. Unfortunately, I never got to see Rin’ live, before they split-up, but as a koto player myself, I wouldn’t include a mid-performance re-tune as a highlight in any video presentation of my concerts. Usually, changing two or three bridges can be done quickly whilst introducing the next piece, but if it requires a major re-tune, then I have two or three kotos set up already in the different tunings and just switch kotos.
Interesting thing with this! In my experience, pretty much any fusion artist at a concert playing any kind of Wagakki has multiple on hand.
I recently got the Wagakki Band scorebook, and in the interviews with the members it says Beni Ninagawa, the Tsugaru-shamisen player, has four on hand tuned to different keys, and the shakuhachi player Daisuke Kaminaga plays up to 8 different shakuhachi throughout a single show.
What I find kind of funny about it is how with other instruments, as Michael said sure you wouldn’t include that as part of a highlight reel, but in the Tsugaru tradition we do choushi awase and the tuning becomes an integral part of the song. 
but if it requires a major re-tune, then I have two or three kotos set up already in the different tunings and just switch kotos.
That is a serious lot of kotos. :'D
But I think this applys to any kind of gig with actual instruments, you always should have 2-4 at hand.
Okay, a shamisen is quickly retuned in between songs but anything else would stop the flow of a show.
Speaking for myself, I usually need up to 3-4 Guitars or other instruments,
Thank you for the exaustive reply! I have understood
Also, I have another question. If someone saw the DVD of Rin’, do they have other instruments? Like other kotos?
“Rin’, do they have other instruments? Like other kotos?”
Yes they do. Typically, the three members of Rin’ play (standard) 13 string koto, Jushichigen (17 string bass koto), nagauta shamisen, shakuhachi, and biwa. (Plus vocals of course).
No, I mean not a different type of instruments, because I know that they play different instruments, but for example three kotos tuned in another way… and also, since I do’n’t know, who standardly plays koto? Who 17-strings? Mana or Chie standardly?