@Ayu_Love I used Topaz Video Enhance AI. It works better with videos that were shot in HD to begin with.
Gackt also had one video with キャイ〜ンのティア and Kumi in his channel. They do a lovely version of Ai no Uta, they all sound very good together! Now I want a Gackt and Kumi collaboration.
Also, here it is Dreaming Now PV and Lucky Star Tour version
https://www.bilibili.com/video/BV1oU4y1p7Ja
https://www.bilibili.com/video/BV1cA411T75r