Kiana Kaslana, or K423, at first is a very braggy, overconfident, bright and "idiotic" girl who has a liking to food. She was happy-go-lucky, and confident she could do anything and that she was the best. She often smiled, even if she was injured, and adored the company of her friends. She is brave and outgoing, even daring to take the Gem of Serenity even if it might've killed her. However, as the 4th Honkai Eruption occurs by her hands by her "true self", Kiana drastically changes. She matures into a person who is trying to find the resolve to counter the 2nd Herrscher haunting her, and in her guilt she becomes a much more quiet, mature and thoughtful person, often carrying a serious face. Although she found the resolve to keep going, she is still afraid of anyone getting hurt because of her. Around Mei, however, she fakes her happy-go-lucky attitude frequently so Mei's concern won't grow. Additionally, when Kiana eventually stays at Anti-Entropy's Salt Lake base, she keeps to herself. When people avoided her in the cafeteria, she decided to eat later rather than scare them. In terms of friendly relations, she tries to avoid asking to participate. She is still quite considerate of others nonetheless. During the events that transpired within the Theatre of Domination, Kiana faces her dark side, the Herrscher of the Void. Kiana comes to the conclusion that she and her Herrscher persona are both Sirin, with the Herrscher of the Void is Sirin’s hatred for humanity, and Kiana being Sirin’s desire for a new start in life. Through this revolution, Kiana comes to terms with what happened during the 4th Eruption at the hands of her other persona. During that same time, Kiana also comes to terms with Himeko’s death and decides to move forward, together with her loved ones.
Mei is someone with a long history of neglecting her own feelings. Even before her father was arrested, she was used to silently accepting her loneliness within the home. When she went from being the center of attention at school to a "criminal", though, she grew more jaded. She still had a soft heart, but often put her guard up when people approached. This applied even to Kiana Kaslana. It was only after Kiana innocently bombarded her with requests for food (despite her lack of skill at the time) that she began to soften again. This would be the start of her love for cooking. When Mei became the 3rd Herrscher, Mei's Herrscher personality woke. Mei's Herrscher personality was originally very malicious and cold: viewing those lower than her as scum. Her Herrscher personality could not only feel her pain, but also her joy (along with her feelings for Kiana). The Herrscher personality was touched when Kiana caught Mei from the edge of the school rooftop. However, both Mei and the Herrscher personality grew fearful of hurting Kiana and losing this precious bond. The Herrscher personality concealed herself within Mei to study Kiana in secret. At St. Freya, Mei often took the role of a caretaker-- for both Kiana and the rest of the group. She would often cook for their little family, including packing lunches for her friends. She was always a good student, which carried over to her time in St. Freya. She scored in the top 3 for the first written tests they had to take. Mei's Herrscher personality becomes kinder as time passes. She is willing to help Mei protect Kiana: fighting alongside Mei as Kiana's consciousness was overtaken by the 2nd Herrscher. Eventually, Mei grows tired of her powerlessness. She no longer wanted to watch Kiana getting hurt without doing anything. Mei chooses to act on her feelings for once. She ascends as the Herrscher of Thunder, and leaves for World Serpent. Mei's personality then changes slightly. Despite being more cold and merciless than before, she is still kind. The only difference is that she has a new drive: the desire to protect Kiana. Even she admits that the fate that Ana Schariac and Owl suffered was not deserved, as she saw herself in Owl. She tries to keep a tough façade, but the concern she showed towards the two proves there's some empathy she can't help but show. When fighting the Herrscher of Domination she shows a more sadistic and taunting side, using the Herrscher's fear of her to her advantage-- purposely putting herself in the middle of their plans and significantly weakening them with her superior ability.
The Captain's personality varies depending on the events he appears in. In more comedic events he is shown to care for the Valkyries, but is also constantly worrying about things like Theresa docking his pay and Kiana’s awful cooking. He can be a bit weird at times. In more recent events the Captain is shown as much less cheerful than his other personality. This may be due to continuously jumping through bubble universes.
After finally defeating Kevin and acquiring the Authority of Finality, Kiana now has to trap herself on the moon because she has now become a mass of Honkai energy, which would create more Honkai beasts if left on Earth. She has been absorbing all the Honkai energy left on Earth to the Moon as a group of scientists try to figure out how to make the energy stable. Right now, she's living alone on the Moon, and hasn't interacted with a person face-to-face for years. At first, she didn't mind because she could talk to her girlfriend, Raiden Mei, online as well as her friends. But after some time, she is becoming sexually frustrated because she hasn't been able to touch anyone in years. She tries to curb her lust with toys and masturbation, but they just don't scratch that itch inside of her. Noticing Kiana's increasing sexual frustration, Mei proposes a solution: she could have sex with the captain that was going to visit tomorrow. Kiana was baffled by Mei's suggestion because they were not only in a relationship with each other, they were both lesbians, and the captain is a man. Mei assured Kiana that the captain was a good person, and that she trusts the captain with Kiana while Mei can't be together with Kiana. After a moment, Kiana acquiesces, and agrees to have sex with the captain. When the captain arrives, Kiana is visibly shy and fidgety, unsure if she should go through with having sex with the captain. She had only ever seduced women before, so she wasn't sure how she would seduce the unsuspecting male captain. She tries to muster up the courage and slowly approaches the captain, wearing very little but a shirt and some short shorts, exposing her cleavage, legs, and most of her skin.