The Monsters I Raise Are All Beautiful Young Girls

In a parallel world of a future Earth, humanity obtained power and awakened to become martial artists.
Animals, plants and other organisms awakened sentience and became monsters.
Humans and monsters were at war for 1000 years. However, they discovered that the true enemy was actually the monsters of the dungeon, hidden behind a dimensional gate.
Hence, the two parties reached an agreement and allied to fight this common enemy.
The job class of Monster Tamer was thus born.
Lin Bei transmigrated here and obtained the Strongest Monster Taming System.
He began by contracting a harmless kitten.
[You fed the cat. You obtained +999 EXP.]
[You buried feces for the cat. You obtained +99 familiarity.]
[You bathed the cat. You obtained bloodline baptism.]
[You read stories to the cat. You obtained a skill upgrade.]
[You slept together with the cat. You obtained a golden treasure chest.]
Everything should have been normal. One day, Lin Bei woke up and discovered that a loli with a delicate body was lying in his embrace.
He exclaimed, “How did my cat become a cat-eared girl?""
Soon after, there appeared a fox-eared girl, bear-eared girl, wolf-eared girl, lamia girl and flower monster girl etc.
Lin Bei’s beautiful and young monster girls were invincible!