On rare occasions, he transforms to a female alter-ego called Tomoko through a quantum converter made by Synapse, and mainly uses this new form to blend in with the other girls so he can peep on them unnoticed.
However, if Tomoki becomes sexually stimulated for too long while as Tomoko (or any other object), the transformation will end and the converter will short out. A small note is while all of the other characters are drawn in their original parameters, Tomoki is mostly drawn in super deformed parameters, with the only times being drawn in his original parameters is when he is serious or feels relaxed.