He created the art work between 1990 - 2000, only in this 10 years, and since then he has stopped continue creating.
So whatever exists today are the only his artworks.
His early work have editions written on the pieces, later in the phase he has stopped putting editions in the work.
His work is created by the same method as Japanese Ukiyo-e (Japanese Traditional Wood Block Printings),
these Ukiyo-e printings used be the one of few entertainment that ordinary Japanese People could have in old era.
So Otomaru felt empty creating limited numbers of works, this is the reason why he has stopped putting numbers of editions on his works.
He wanted to create something to let many people enjoy his work, so he put very reasonable price on his works.
This is almost with no profit, only with materials and small fee for his labor.