No idea about the name or copyright of the two characters in the poster between Minoriko and Sakuya & Remilia's posters. Oh and tried to find the socials of the illustrator of the 东方LiveParty poster, 白野威 but had no luck.
Basically, Hikari is known for being able to push buttons incredibly fast. The enemy depicted in the video game she is playing gives a large number of points if killed before it assembles itself, but takes 12 shots to kill. You need to be able to press buttons very, very fast to do this quickly enough.
