"Shin'ai (深愛)" is the 19th single by Japanese singer and voice actress Nana Mizuki, which was released on January 21, 2009, by King Records bearing the catalog number KICM-1270.

composed, arranged, and produced by members of Elements Garden, Miki Watabe, Yōhei Sugita, Hibiki, Sayuri, and Nishi-ken.

The single reached number 2 in Japan's Oricon weekly singles charts for the week of February 1, 2009.

[1] Total Sales: 62,869