Tomatsu released her fifteenth single "Step A Go! Go!" on October 12, 2015. This was followed by her sixteenth single "Cinderella Symphony" (シンデレラ☆シンフォニー), which was released on February 29, 2016. She then released two best albums titled Tomatsu Haruka Best Selection (Sunshine) (戸松遥 BEST SELECTION -sunshine-) and Tomatsu Haruka Best Selection (Starlight) (戸松遥 BEST SELECTION -starlight-) on June 15, 2016.  In July 2016, as part of Sphere, she made her North American live debut at Anime Expo.  Her seventeenth single "Monokuro/Two of Us" (モノクロ/Two of us) was released on November 7, 2016; the song "Two of Us" is used as the theme song to the video game Sword Art Online: Hollow Realization.  Her eighteenth single, "Uchōten Traveller" (有頂天トラベラー), was released on October 23, 2017; the title track is used as the ending theme to the anime series PriPri Chi-chan!!.  She released her fourth solo album Colorful Gift on May 14, 2018.  Her 18th single "Try & Joy" was released on September 5, 2018.