User blog comment:Jopjopjop/Volume 19 Spoilers/@comment-25792629-20150531215445/@comment-16281343-20150601190302

v21 is Vali's. -SLASHDOG- gives something about Vali when he was younger.

Short stories are always there in case of something like these were a character's development cannot be included in the main volumes. So, we'll get to know more about him sooner or later.