Porn Game: Hoshizora no Babylon -Semarikuru Cosmic Sukebe Onee-sans- Final by One-Up

The year is 2068 in the Universal Century.
It's an era where men are overwhelmingly outnumbered by women.
The setting is the Ganymede Station near the vicinity of Mars in the solar system.
Our protagonist, Ginga Amanokawa, belongs to the spaceflight department of the academy.
While on a space navigation test aboard the colony ship "****lon," they are suddenly attacked by a space monster girl
named "Cosmic Race" that appeared from the other side of a wormhole.
These girls, with a humanoid female appearance, have a goal to mate with human males for the purpose of reproduction.
Despite their inexperience, under the command of the ship's captain, the protagonist and the heroines manage to successfully repel the enemy.
However, as Ginga's existence as a "precious human male" becomes known, they find themselves continuously targeted by the Cosmic Race...!?​

Hoshizora no Babylon -Semarikuru Cosmic Sukebe Onee-sans- Final by One-Up game preview

online.