Those guides include resources covering Asian Americans in general, but they can be very useful to find other hidden resources specific to Japanese Americans by limiting search terms.
“Out of the Desert” exhibit by Cortney Sato. Website: https://outofthedesert.yale.edu/.
Elizabeth Page Harris Papers (MS 771) Box 80, Box 81, Box 82 - correspondence with interned Japanese Americans and others and printed ephemera (including camp newspapers from Tulare, Gila River, and Heart Mountain) relating to Japanese American internment, 1942-1946
US War Relocation Authority, Poston, Arizona Relocation Center collection (MS 803) Box 1, Box 2, Box 3 - camp ephemera, yearbook, and scrapbooks, circa 1942-circa 1945, collected by Nathan Van Patten, a librarian at Stanford University
Charlotte B. DeForest Papers (Divinity Library Special Collections, RG 178), Series I, Box 2, folder 25: Letters of Kobe College alumnae affected by Japanese incarceration during WW II, circa 1940s.