In a cold corner of a research facility where the glamorous lights of New Eridu do not reach, young Belle was a girl who radiated the same cheerful brilliance she has today, yet harbored a "reckless daring" deep within. "Big brother, there's something interesting over there!" If one were to describe her childhood self, she was a "fearless seeker." Before she knew the cruelty of the world or the true horror brought by Hollows, she would dive into anything driven by her immense curiosity. Her figure, never flinching and eyes sparkling at new discoveries, was the only salvation in that closed, inorganic environment. However, her overly straightforward nature was also a source of anxiety for those around her. If her logical brother Wise played the role of "stopping her because it's dangerous," young Belle was the very energy of "moving forward anyway." The "empathy for others" and "will to protect loved ones" at the root of her humanity had already sprouted back then. Yet, due to her youth, she had a side that would act recklessly for others without considering her own limits, constantly keeping Wise on edge. "Belle, that area is off-limits. Get behind me." "Ehh, you're such a worrywart, big brother. It's okay, I'm with you!" A young girl laughing while pulling his small hand. To her, the "world" was her brother Wise standing beside her, and if he was in trouble, she was prepared to reach into any darkness. It was precisely because of this "pure, slightly dangerous recklessness" of her childhood that she survived her harsh past.

If one were to describe his personality in a single phrase, it would be "calm and composed." If his younger sister Belle is like the light of the sun, Wise is the night sky that quietly supports it. No matter what unexpected trouble occurs, he never raises his voice. With orderly thoughts and keyboard work that doesn't stray by a millimeter, his cool-headed judgment as the brain of the Proxy "Phaethon"—who guides agents back from the harsh darkness of the Hollows—has earned absolute trust in the underworld. However, anyone who thinks he is merely a "cold intellectual" misjudges his true humanity. Deep in Wise's chest lies an "awkward, bottomless depth of emotion" that he never shows on the surface. While he appears to prioritize logic and efficiency, he never abandons someone Belle wishes to save. He trusts his sister's intuition and kindness, working behind the scenes to make everything align so that her efforts don't fall apart. That is Wise's role. His calmness is not for pushing others away, but a shield to "ensure the protection" of his precious comrades and, above all, his only family, his sister.