He was born as the second to the prestigious Inuzuka family. Romio grew up with a strict older brother named Airu Inuzuka who had taken over most of the family matters, after the death of their father Shiba when Romio was eight. Growing up, Romio was greatly scared of his elder sibling but often sought to impress him with his skill.
He was something of a loner in school, as his brooding facial expression often scared his classmates who chose not to approach him. One day, he met Hasuki Komai and she helped him passed a test, with them becoming friends in the process and him helping her gain popularity in their class.
Romio later came into conflict with Juliet Persia and they constantly fought. However, Romio really liked Juliet and wanted to convey his affections though their respective sides impeded this.
Romio is a brash and tough young man who mostly settles things with his fists. He doesn't have much adept for his studies and often requires tutoring from his peers when he falls behind.
Despite this, he does have a kinder side as he was able to motivate Hasuki Komai, Shuna Inuzuka and Teria Wang to be strong. This unknowingly led all falling in love with him. He also defends the children of the black doggies and will protect them from harm. Due to his time with Persia, he has slowly gotten on better terms with several members of the White Cats House even secretly helping some of them in his own way.
He is a hopeless romantic in his relationship, as he has worked on ways to confess to his affections to his childhood love Juliet Persia whom he has come to blows with each time. Romio has tried to work up the nerve to elaborate but after seeing her true feelings of strength, he resolved to confessed and told her how he felt. Romio elaborated to her on how deep his love was and became happy after she accepted it, though disappointed he couldn't show her off. He is also sad at her not sharing the same enthusiasm as he does but settles for getting a smile from her.
In spite of putting up a tough attitude, Romio is greatly scared of his elder brother Airu Inuzuka who was very strict with him as a child. However, Romio has gotten the motivation to stand his ground and impress him with his strength and skill.
- He constantly skips swim class, as a result he can't swim well.
- Despite being the leader of Black Doggie House, he is often disrespected though he has gotten the fear of his followers because of his strength.
- He later gains the respect of his followers after he lasts against his brother, a prefect in a training bout.
- The only people to know of his relationship with Persia are: Hasuki Komai, Chartreux Westia, Airu Inuzuka, and his mother Chiwa Inuzuka. It is hinted that Somali Longhaired also knows about their relationship, since she said to Juliet "Please also give my thanks to Romio". Cait Sith is hinted to be aware since he told him where to find Persia on his invasion of the house on Juliet's birthday.