If you're looking for manga similar to Trans Horizon, you might like these titles.
A girl had a dream of singing, and she was scouted by accident on the street by her producer. But the producer said her voice was too low to be a female singer, so the producer decided to dress her like a man and told her to sing in a duo. But then the girl got married, which led to the story that is being told of her hiding her secret identity to others as a popular male idol.
Fang Minzhu was a small agent in the show business. She was introduced to the most popular idol girl star, Liang Youxi, as a life agent. But Liang Youxi asked for a male agent. Minzhu, who was desperate for work, gritted her teeth and applied as a boy, but Liang Youxi was very secretive. "I chose a boy so I can keep you away from my private life openly." It's so strange when an actress said that. In an unexpected situation, Minzhu found out about the secret of Liang Youxi...
Mahoro Harukana moves to Tokio to achieve the dream of becoming an Idol. In order to do this, Mahoro will assist to the National Entretainment and Music School in Kamisaka. Everything goes surprisinly well, being great at singing and dancing, and even her teammates are astonished by her talent.The only problem is that... Mahoro is actually a boy, and a boy who wants to become The King of the Idols!
High school first year Sara has a secret…she’s really the super-popular singer SALA! However, as an idol her gender is kept a secret from the world in order to sell her music. But can Sara win when she wants to be just Sara…?
Kana Kanzaki's younger brother, Kanata Kanzaki, is the lead of the new idol group, RUSH. On the day of their initial debut, he went missing and Kana was asked to take his spot...?
For the sake of his little sister, a boy tries his best at becoming a star gravure idol.
Cha Hyeseong watches his crush drift away into stardom. He tries to preserve their relationship by enrolling into a school that produces idols -- the same one she attends. He's immediately assigned to debut in an idol group that focuses on acting, which brings more trouble than he asks for.
Marimo Himenogi desperately wants to become an idol singer. When a local contest is announced, she begs her boyfriend, Ayumi to sing as her partner. Ayumi relents, and disguises himself as a girl so that he and Marimo can enter the singing competition. Surprisingly, they win and are signed to a recording contract as a new group called "Twinkle." Now they must keep their newfound fans from finding out that Ayumi is actually a boy.