He started as a low-ranking army officer and is the sole remaining retainer in the Hong household. Seiran was taken in thirteen years ago by Shoka Hong, and he has made a vow to spend his life repaying that kindness, helping the Hongs by protecting them, performing repairs, and taking small guard jobs to earn money. He is a very skilled fighter and swordsman, and despite his amiable disposition, he could be quite ruthless to those who put his loved ones in danger and conforms to the idealism of "the end justifies the means." He often puts others' well-being before his own and preferring to support others by watching and helping from the shadows. He has known Shurei ever since the latter was little, thus is very protective of her, usually following her in order to guard her, even when she does not know it. The two are often mistaken for a couple due to the amount of time they spend together, but neither of them show romantic feelings for the other.

Seiran is later revealed to be the previously exiled second elder brother of Ryuki, Seien, whom was the only one to ever treat Ryuki nicely. He was known as the "flower" of the royal princes due to his handsome looks, kind heart, and also his physical and intellectual superiority over his brothers. Because of this, his brothers grew jealous, and after his mother, who hated his existence, and grandfather conspired to make him Emperor, he, along with his mother, was exiled. The other royal families sent assassins to kill him, and though he did away with them, his mother was killed in the process. Sometime later, he is brought into the Satsujinzoku, a murderous band of thieves in Sa Province (Brown Province) where he was nicknamed "The Little Whirlwind." Ensei Ro joined the group as well, and the two destroyed the band themselves. After leaving Sa, the Hong Family comes across him and takes him in, with Shokun giving him the name "Seiran," meaning "Silent Orchid," as well as him receiving the surname, "Shi" (pronounced the same as the Emperor's family name, but has different kanji). He decided to wholly devote himself into being "Seiran," and does not let anyone get near his past, though some characters throughout the series discovers his true identity. Though he claims to be 21 years old, he is 26 years old at the start of the series.