All inputs are my own, but after checking against John's TAS, there is no time saved in gameplay.
The main reason for this submission is that current rules require the BIOS to be enabled and included in the timing. As the run is extremely short, this timing difference has a significant impact. I asked John if he would be willing to update his TAS rather than having me submit this, but he said it would be easier for me to submit it instead. Depending on the publication technicalities, I'm also happy for this button file to update the existing publication rather than create a new one if that's a possibility.
In terms of my own research with this game, I've tried various different strategies in the shop. Use of the up and pause buttons can manipulate the outcome of the glitch, but I couldn't trigger the credits without using John's setup. More research is needed on this glitch as I feel that the TAS could come much lower.
Below is John's submission text as there is lots of useful information in there.
John's Original Submission Text
Ys: The Vanished Omens is normally a game about exploring the world, defeating bosses, collecting items and experience and saving the world. Thanks to how broken the mirror inside Pim's shop is, however, Adol decides he doesn't want to bother with any of that pesky exploring business, and instead warps himself to the end of his journey.
Game objectives
.Warp to credits
.Corrupts memory
I have been running this game RTA for some time now, using the same route as the TAS this obsoletes. I discovered by pure coincidence that certain vertical scrolls allow the credits warp to be triggered without entering the in-game menu. I wanted to see if this would save any time, and the result is this TAS, which saves 21 frames over the previous by CoolKirby.
Minea Village
All of the overworld portion takes place inside Minea Village. Where the previous TAS scrolled vertically so that the bottom pixel visible is the bottom pixel of the middle set of buildings, the new setup requires that you instead go 8 pixels lower. This costs a total of 16 frames of additional movement. The horizontal scroll remains the same.
The main time save in this TAS comes from not having to enter the menu. This saves 37 frames.
Pim's Shop
The menus are identical to CoolKirby's TAS. The mirror is bought, then buying it again is attempted 3 times. Leaving the shop at this point triggers the credits warp.