Unmarked spoilers are ahead, per Spoilers Off rule.
The manga, while not focusing on it too much, it also doesn't gloss over the fact that almost everything that Akihito has suffered is horrifying. He's been kidnapped by members of various criminal organizations on separate occasions, and he's been sexually assaulted in all these cases. The fact that he's a relatively regular individual violently thrust into this dark underworld is pretty terrifying too.
Finder no Rakuin has Fei Long at the mercy of his adoptive-brother, Yan Tsui. From fearing for Tao's life to having to submit to his brother's violence and sexual assault (including a rape attempt stopped at the very last second) to the despair he feels that he starts blaming himself for what's happening, there is ample reason for sleepless nights.
After hinting to it in Naked Truth, the origins of the scars on Mikhail’s back are revealed in Pray in the Abyss. As a preteen he was physically abused by his uncle Yuri because Mikhail was blamed by the latter for his ephebophile urges. Despite the nonchalant reveal by Mikhail in Naked Truth, Pray in the Abyss showed that he was actually traumatized by the abuse he had suffered. Being tortured again by the same man reawakened the trauma, to the extent that Fei Long allows Mikhail rest his head in his lap after initially refusing him. Though Mikhail confirmed that the abuse did not evolve past physical beatings, it is still horrifying that he had been subjected to such treatment by someone who was not only supposed to be a trusted family member, but also someone who was supposed to be taking care of him.
