Although she initially appeared as a kind and compassionate person, Seryu is ruthless, psychotic and unstable. She was seen to enjoy killing to a high extent those of whom she considered to be evil, almost as if it was a hobby.

She has a strong fixation upon "Justice", originating from her father's service in the Imperial Army and subsequent death. She also highly respected Ogre the Demon, her superior and teacher, and was heavily anguished by his death as well. Her opinion of justice is blunt, as she believes Night Raid is evil for their actions as assassins, but believes killing in service to justice is always right, which ultimately makes her opinion of murder similar to theirs, if not completely the same.

Seryu has a twisted sense of right and wrong, bordering on a completely black and white view of the world. All the people who serve the Empire, despite the deeds they do both publicly and discretely, are considered good by her, while those who oppose it, even those who are forced against their will, are pure evil. Her twisted view of justice has caused a level of distrust towards her by her own teammates, as well as the entire imperial forces on occasion, as she brutally murdered a group of prisoners before they could interrogate the group.

This sense of right and wrong is so twisted as she lacks mercy of any kind. She has stated that evil deserves no mercy, which is ironic as that is the one thing that separates justice from vengeance or even common murder. If nothing else, Seryu is ultimately convinced that she is doing the right thing in what she does but her actions tend to be far more brutal and insidious than those of the people she believes to be evil.

When she presented herself in a calm way, Seryu's is eager to help out people in need. She is often seen idolizing her superiors and showing deep sorrow upon hearing the news of their deaths. Overall, taking into account her simplistic view of the world, hero worship, and sometimes childish behavior, Seryu has quite an immature personality with a streak of emotional instability.