it looks like a huge red leech is sucking on her butt, perhaps trying to suck something out?

Selvokaz said:

it looks like a huge red leech is sucking on her butt, perhaps trying to suck something out?

Knowing how these usually go it's probably injecting, but it could go either way.

ズル normally the Japanese onomatopoeic sound for sucking I believe.

Selvokaz said:

it looks like a huge red leech is sucking on her butt, perhaps trying to suck something out?

Seeing how this is Ishimura, and this woman seems to have a "Cell tail", she apparently "ate" something.