Nikkei Trendy, a Japanese magazine, has reported in its latest issue that a "3DS Lite" is in the works. According to the magazine the new 3DS will be thinner and have better battery life.

Nikkei has a very good track record with rumors. It previously rumored Project Cafe (the Wii U) to include a 6inch touchscreen, camera, and mid2012 release; a gaming phone by Sony (Xperia Play); 3G and an OLED touchscreen for the PlayStation Vita (or PSP2, before the name was announced); and Wii Fit Plus and Super Mario Bros. Wii.
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