Riyu Momose (百瀬リユ Momose Riyu?) is a main character and a female protagonist in Akiba's Beat. She is a 14 year-old girl and a popular Japanese idol who resides in Akihabara as one of its poster girls, as well as often holding a mini live handshake meeting which led to her experiencing the "eroded delusion". She has a love for rabbits and cherry blossoms. She later becomes close friends with Kotomi and Saki. She is known for her nickname "Rippyon" by fans.
She carries the title, "The Ever-Smiling Idol" (笑顔満天なハッピーアイドル?).