Just an idea, but I've been kicking around the internet looking at the different influences behind Ikuhara and A.J. Seazer.  What I found was that Seazer worked with Tenjou Sajiki https://en.wikipedia.org/wiki/Tenj%C5%8D_Sajiki for a loooooong time.  Do you think that's where Ikuhara got Utena's last name?  Knowing his love of theater and all I feel like this is very likely.