Koya Rosado Elliott (エリオット・ロシャード・昂矢 Eriotto Roshādo Kōya; born September 21, 1987), better known by his stage name Elly (stylized as ELLY), is a Japanese dancer and rapper. He is a performer(dancer) of J-Pop dance and vocal group Sandaime J Soul Brothers and a former member of Gekidan Exile.

For his solo career as a rapper he uses the stage name CrazyBoy. He debuted as a soloist in collaboration with Exile Shokichi in the song "THE ANTHEM" on June 4, 2014, and released his first solo album NEOTOKYO FOREVER on July 4, 2018. As a member of Sandaime J Soul Brothers, he has received the Japan Record Awards twice and he has choreographed some of the most famous dances for his group, including the famous "Runningman" dance of R.Y.U.S.E.I. He is also an enthusiastic Fortnite player, hoping to promote e-sports in Japan.

Elly's father is former OPBF Super Welterweight Champion Carlos Elliott [ja] and his younger brother, Likiya, is also a dancer and leader of the J-pop dance and vocal group The Rampage from Exile Tribe.

Elly was born Koya Rosado Elliott on September 21, 1987 in Misawa, Aomori Prefecture to a Japanese mother and an African-American father. His father is former OPBF's Super Welterweight Champion Carlos Elliott and his younger brother, Likiya, later followed the example of Elly and became a dancer too. When he was in junior high school, his friends gave him the nickname "ELLY", which is short for his surname Elliott, and he continued to use "ELLY" as his stage name. Elly had played baseball since he was young and was the catcher and the fourth player in the batting order (the cleanup hitter, often the one with the most power and ability to drive in runs with extra-base hits) in his high school baseball team. After losing to Hachinohe Gakuin Kosei High School in the Quarter-final of the Regional High School Summer Baseball Tournament in his third year, Elly's dream to play in Koshien ended. One of his opponents in this crucial game was Sakamoto Hayato, who continued to become a professional baseball player and still remembered Elly as his opponent when the two met after they both earned fame in different fields. Elly entered Tokyo University of Agriculture with a baseball scholarship, hoping to become a professional baseball player after his graduation.

Elly began to dance and produce music at a very young age. Since there is an American Military Camp in his hometown Misawa, he grew up in a city with much influence from American culture. He bought a set of DJ equipment with his pocket money when he was still a sixth-grade elementary school student, learned how to DJ from the manager of the local CD shops and started to rap soon after in junior high. In high school, he started dancing after seeing B2K's film You got served. He was amazed by the dancers in the movie, and learned his first dance moves by imitating the dances from the film with his brother. After he moved to Tokyo to attend university, he continued to practice dancing at night after a day of baseball practice. It was during these busy days when he saw the performance of the dance team "BASE HEADS" at a club in Shibuya, that he decided he wanted to be a dancer just like them at the very moment. As a result, he quit university and baseball in the second year of his studies, chasing his dream to become a professional dancer.

Elly formed the Hip-Hop dance crew THE TEAM in 2007, which marked his debut in the professional dance world. Apart from performing at clubs and events, he also appeared as a backup-dancer in the music videos of singers like Toshinobu Kubota and Meisa Kuroki. In March 2010, Elly was scouted by EXPG Studio (a talent school run by LDH) to perform in Gekidan Exile's play NIGHT BALLET as a guest dancer. He joined the actor group Gekidan Exile Kazegumi (the team of wind) in April of the same year, officially joining LDH at the same time while remaining hopeful about becoming part of one of their dance and vocal groups in the future. In May 2010, he performed in Gekidan Exile's 4th play DANCE EARTH ~Negai~.

On July 19, 2010, when LDH announced that they wanted to revive dance and vocal group J Soul Brothers and form Sandaime J Soul Brothers, Elly was selected as the first member (performer) of the new group, joining Naoto and Naoki Kobayashi, who were also members of the previous J Soul Brothers line-up. On September 27, Elly made his first public appearance as a performer of Sandaime J Soul Brothers during the Fantasy Goya-sai: Exile Tamashī (FANTASY後夜祭～EXILE魂～; FANTASY Late Night Festival ~EXILE Soul~) live performance from Exile at Toyota Stadium. On November 10, he made his major debut as a member of Sandaime J Soul Brothers as the group released their debut single, "Best Friend's Girl", debuting at number three on the Oricon Singles Chart.^{[citation needed]} On July 19, 2011, He officially withdrew from Gekidan Exile.

In August 2012, Sandaime J Soul Brothers' seventh single "0 ~Zero~" which included their major hit "Hanabi", was released and became their first single to sell over 100.000 copies. Elly choreographed the dance for "Hanabi", which marked the first time he choreographed for his group. At the end of the year, Elly and his group appeared on the stage of NHK Kohaku Uta Gassen for the first time, performing their single "Hanabi".