Inro
Not necessarily. There are different types of kimono and various events that may or may not need the "small pillow" on the kimono sash.
kimono (outer layer), naga juban (under kimono layer), obi (the sash around the waist).
The middle 'sash' that wraps around the kimono is called an obi.
Netsuke
A broad Japanese sash, usually with a bow in the back and worn with a kimona, is called an obi.
A kimono sash is called an Obi.
There is an elastic clip/belt that is worn under everything that helps hold the kimono closed called a 'korin belt', but I believe you are thinking of an 'obi' it is the thick sash-like cloth that is tied around the waist/torso when wearing a kimono.
Obi (a sash worn around the waist of a kimono) and overalls are clothing items. They begin with the letter O.
The waist sash that goes around a person's torso when wearing a kimono is called an Obi. However there are quite a few unseen under layers and wraps that actually work to hold the kimono closed, that are known as a korin belt and koshi himo ties. The obi is just there for looks.
An obi [Japan, female] is part of traditional kimono garb.
it is called an Obi
Overalls and overcoat begin with O. An obi is part of traditional Japanese dress. It is a sash that is word around the waist of a kimono.