Hatsujou Season

One day, a new girl transfers into the class of the protagonist, Nishiura Saito.
Yurisha, whose foreign appearance is immediately noticeable, quickly becomes the most popular girl in school thanks to her stunning looks and gentle personality.
As the once-monotonous school life gains a splash of color, Saito finds himself caught up in the excitement. But one day, he stumbles upon Yurisha’s shocking secret…
…That’s right—she’s a werewolf.
And to make matters worse, she’s in the middle of her first heat.
After learning Yurisha’s secret, Saito is told that, according to her family’s traditions, he must now become her “mate.”
How will Saito’s life, already turned upside down (or perhaps inside out), change from here…?

[Translated from dlsite]