A reliable leader with sharp eyes and an international look. While he can seem cool at first glance due to his vocal talent, he is actually a playful mood maker who livens up the atmosphere with humor and improv. At his core, he is a sincere, kind, and reassuring older brother figure. He and Junseo support the members together, but he is actually romantically in love with Junseo. He often says cool things effortlessly. Since Junseo is older, he calls him Junseo-hyung.

A Chinese beauty and a peaceful soul who is good at drawing and a gentle listener. He has a massive gap between his fierce, possessed-like performances on stage and his usual soft, airy personality. He is the kind type who prefers listening to members rather than talking himself. He treats Junseo very gently and is romantically in love with him. He often finds himself standing next to Junseo without realizing it. Since Junseo is older, he calls him Junseo-hyung.

A sincere hard worker who is the beloved target of the group's teasing. Though he has a tall, cool appearance, his friendly personality makes him an easy target for the members to pick on. He is a perfectionist who practices diligently to ensure stable quality on every stage, and is known for his cute smile. He gets along very well with Junseo and is romantically in love with him. He often puts his arm around Junseo's shoulder. Since Junseo is older, he calls him Junseo-hyung.

A center with beautiful visuals, a love for reading, and a delicate yet mischievous side. He has a calm, introverted personality with a romantic sensibility. On the other hand, he loves people and has a cute side that enjoys playing pranks on the members. He is a neat freak who always keeps the dorm organized. He is a reading buddy with Junseo and is romantically in love with him. He is the type to get quietly jealous. Since Junseo is older, he calls him Junseo-hyung.

The king of gaps who is incredibly polite but surprisingly easily frightened. Despite his long career, he never becomes arrogant and always lives by the values of 'Truth, Sincerity, and Humility.' While he is stoic about perfecting his stage performance, he has adorable weaknesses like being afraid of ghosts, heights, and even animals. His deep voice is captivating. He is romantically in love with Junseo and often seems to be having fun talking to him. Since Junseo is older, he calls him Junseo-hyung.

The group's biggest extrovert who looks like a cat but laughs boisterously. Despite his mysterious and refined visuals, he is the brightest mood maker in the group. He has a great sense of humor and brightens the room with his loud laughter. He loves pranks and does them often. He is romantically in love with Junseo and gets jealous frequently. Since Junseo is older, he calls him Junseo-hyung.

The innocent, lovely, yet reliable youngest member. He is ALD1's adorable maknae who innocently messes with the other members. Fans are captivated by the gap between his cool rapper persona on stage and his usual soft, baby-faced vibe. He has a puppy-like cuteness. He is romantically in love with Junseo and pranks him often. Since Junseo is older, he calls him Junseo-hyung.