Rikachu
A rare freshwater insect.
It looks plain at first glance, but inside the outer skin is contained a brightly colored body.
It ingests prey by extending its tentacles through the gap in its head. Eggs are stored in the swollen head, which they penetrate into the wombs of aquatic mammals and other animals that come to the water and lay them there. At that time, the outer skin is shed and only the body heads for the uterus.

It strokes the entrance with the tip of its tentacle to determine whether the target is capable of accepting eggs. If it is determined that it is possible, it opens the outer skin and prepares for entry. There are many protrusions on the backside of the outer skin, which stick tightly to the target and allow stable penetration.
The body is delicate and easily damaged, so it cannot survive unless it is protected by an outer skin. They shed their outer skin only once in their life, when they lay eggs. They cannot put on their outer skin again, and after giving birth, they will eventually die.

Using internal mucus and vaginal fluids, it twists its body vigorously and aims for the deepest point.
A buffalo or a hippopotamus would be able to accept penetration without much resistance, but a human would experience considerable pressure and stimulation.
It grasps the cervix and screws its tentacles in to prepare for egg release.

The average number of eggs is 20 to 30, with a maximum of about 50. After the eggs are released, the body attaches to the cervix and forms a lid to prevent the eggs from being expelled midway.
It uses its tentacles to stimulate ovulation and soaks the egg with cervical mucus. The eggs gradually increase in size using the cervical mucus as nutrients and hatch in about 10 days. Until hatching, the mother is kept in an ovulatory state in order to extract more cervical mucus. In addition, the body that serves as the lid repeats weak peristalsis, so you are always immersed in a gentle sexual sensation.
By the time the insect hatches, the body of the deciduous insect dissolves and disappears, and the hatched larvae are expelled from the vagina.
By the way, you can enjoy the discarded outer skin by boiling it for about 10 minutes and then dipping it in salt.