I don't understand. Did Yuuka kill Marisa?
i was a bit confused with this too, because the ending indicates that Yuukas didnt killed marisa, but there is a quote of Alica saying
"It's not like a have a grudge against you, yuuka.
Being prepared for the unexpected is part of the rules of danmaku battle, right?
Marisa's the one one who lost. "
That to me seemes to assign that Yuuka killed Marisa in a danmaku battle.
By any way, i really enjoyd this manga, hope that one day be able to see more of his work