A sex toy like a dildo or strap-on placed over a character's penis, usually as a form of chastity play or sexual denial.
Also includes penis sleeves or penis extenders that are worn over the penis that extends the length of the penis.
Primarily associated to Gikon (偽根), as Pixiv Dictionary defines it:
This SM play involves crushing the penis with a flat chastity belt and then attaching a dildo or penis band over it. This is a humiliating situation that often involves wearing something larger than the original penis.
Because it is not a real penis, the pleasure experienced during intercourse is minimal, and ejaculation is often impossible, or even if ejaculation occurs, it cannot be deposited into the vagina.
In some cases, ejaculation occurs through a dildo and then through a chastity belt. Pixiv Dictionary
