Quick answer — Kouji Kumeta worked on The Eccentric Family 2 (Original Character Design), Kakushigoto (Original Creator), The Eccentric Family (Original Character Design) and 10 more anime.
Kouji Kumeta worked on The Eccentric Family 2 (Original Character Design), Kakushigoto (Original Creator), The Eccentric Family (Original Character Design), Zan Sayonara Zetsubou Sensei (Original Creator), Zoku Sayonara, Zetsubou-Sensei (Original Creator), Goku Sayonara Zetsubou Sensei (Original Creator), KAKUSHIGOTO Theatrical Edition (Original Creator), Sayonara, Zetsubou-Sensei (Original Creator) and 5 more.