Arrested: March 1942
Maui County Jail, Wailuku, Maui Island
Paroled: May 1942
In 1940, Masaru Morikawa was among thirteen members of the Maui Nikkei community who were elected officers of the local Japanese Society. After the outbreak of World War II, all were arrested and imprisoned, some were interned, most had sons who served in the U.S. military during the war. These men were president Seiichi Ohata; vice-presidents Unosuke Ogawa and Motoichi Kobayashi; Japanese secretary Tomeichi Fujii; English secretary Kaoru Nagatani; treasurers Yoshio Yamane, Riichi Shibano, and Robert Sosuke Toda; auditors Kanichi Takitani, Masaru Morikawa, Makizo Kawaharada, Hatsugoro Makimoto, and Ikkei Kawachi.
Morikawa's sons, Samuel Katsuto Morikawa and William Masakatsu Morikawa, served in the U.S. military. Samuel was a member of the 442nd Regimental Combat Team's 522nd Field Artillery Battalion.