Asanuma is the manga version of Shinozaki. In the manga, Ittou Asanuma is a 7th grader at Moto Azabu Junior High. He met Makoto at the Crown. He is also good friend to Mamoru. Makoto trusts Asanuma very much, and even confides to him about being a sailor senshi as well the the identities of the other senshi. He first appears in Sailor Moon manga #4 and later appears duing the Sailor Stars manga.
For more information about Asanuma and Makoto, these two sites have in-depth information. ^.^
Asanuma and Makoto Images