
Quick answer — Mitsuki Tanimura voices Kazuma Ikezawa in Summer Wars, Kaho Fujitani in The Girl Who Leapt Through Time.
Mitsuki Tanimura voices Kazuma Ikezawa (Summer Wars), Kaho Fujitani (The Girl Who Leapt Through Time).
Kazuma Ikezawa is voiced in Japanese by Mitsuki Tanimura.