You do realize that mathematically speaking, Youmu has been speculated to be the fastest person in Gensokyo without the use of abilities, due to her spell card "200 Yojana in One Slash"? Some specific numbers on the topic: "200 yojana can be a distance anywhere from 1,320-3,000 kilometers or 825-1,875 statute miles in length" "her slowest sword slashes have been calculated to move at speeds in excess of Mach 70 (70 times the speed of sound, or 53,200 mph/85,120 km/h at sea level)" "her theoretical top speed was approximately one quarter of the speed of light" Honestly, I wouldn't be surprised if she could create afterimages with mass at such speeds, especially in Gensokyo.
*clap clap clap* ♥I CAN'T!!193I'll help make dinner as well!Amazing!Amazing~ ♥That's nothing!Thank you, but please stand back!You can use the duplication technique, huh.