Shokushu Taikan no Mahou Shoujo ☆ Yuuri

Yuri is the only magic girl who works to combat the isekai tentacle invasion.
Though she fought tirelessly, she was still a novice magic girl, and her wet holes
get drilled repeatedly by slippery tentacles, as they writhe in pleasure!

But these were not ordinary tentacles.
They targeted the wombs of human women to plant a "core" in them,
and multiple their numbers through forced birthing...!

Though Yuri ahe-cried as she was forced to birth tentacles, her senpai Keito
decided to enjoy the mad pleasure that birthing tentacles brought...!?

[From DLsite English]