The very premise of the story is heartwarming in and of itself. Goro Akechi gets rescued from an abusive foster home and adopted by the Dojima family, thereby ending the cycle of abuse and giving him the support system he lacked in canon. Thanks to the intervention of Kanji Tatsumi and the hospitality of the Dojimas, Akechi is given a stable home and fresh start in life, all but ensuring that he won't go down the same dark path he walked in canon.
Akechi's friendship with Kanji is very sweet. After saving him from an abusive foster home, Kanji quickly develops a Big Brother Mentor relationship with Akechi, becoming both a close friend and a positive role model to him.
Akechi's life-changing first encounter with Kanji. The imposing, thuggish-looking teen approaches Akechi on the street only to defy his expectations by crouching down and reassuring him that he means no harm. Noticing the kid's bruises and sickly build, Kanji immediately expresses outrage on Akechi's behalf when it becomes apparent that the latter is being abused. Upon walking with Akechi to his foster-home and finding that his foster parents have locked him out of the house, Kanji gives him a handmade crow plush. Akechi is flabbergasted that this stranger saw his suffering and cared enough to make him a gift. Kanji then calls law enforcement, waiting with Akechi until the police arrive.
Throughout the story, Kanji consistently looks out for both Akechi and Nanako, accompanying them even during the ongoing serial murder case. This earns him the trust of police detective Ryotaro Dojima despite his track record of delinquency.
Much like Akechi and Nanako, Dojima is completely accepting of Kanji's less traditionally masculine hobbies (eg: sewing, knitting) and makes it clear that he appreciates everything he's done for the family.
Dojima: It's unexpected, but who am I to judge? You're keeping outta trouble, and you're keeping the kids safe. With the way things have been going lately, I can rest a whole lot easier knowing they've got someone responsible keeping an eye on them.
Upon learning of Akechi's situation, Dojima immediately offers to adopt him, both to save him from an uncertain future and to give him a stable home. Notably, he goes out of his way to ask for Akechi's consent before making the decision to adopt him. In spite of his flaws, Dojima does his best to give Akechi a loving home, providing him with food, clothes and shelter; a stark contrast to the boy's previous foster parents who neglected him. Thus, Dojima becomes the first person in Akechi's life to fulfill the role of a father figure.
The reason Dojima decides to adopt Akechi? He and his wife Chisato planned on becoming foster parents prior to the latter's untimely death, and Dojima adopted Akechi in order to honour Chisato's wish.
All in all, Dojima is a very down-to-earth guardian. A positive role model who doesn't always stick the landing, but tries nonetheless. Absentee as he may be, he is genuinely kind and loving in the fleeting moments when he is around, and he genuinely tries to be a good parent to both Nanako and Akechi. This actually makes him preferable to Akechi over an idealistic dad, as it shows Akechi that he doesn't have to strive for perfection.
Dojima's choice of words in Chapter 17 indicates that he truly sees Akechi as a member of the family and is grateful to Kanji for bringing him into his life.
Dojima: [To Kanji] But I can tell you've got a good head on your shoulders. Instead of going after Goro's foster parents, you trusted us to bring him home.
Much like her father, Nanako welcomes Akechi into their home with open arms. Upon their first meeting, Nanako greets him warmly, immediately treating him like an old friend whilst taking care to respect his boundaries. Seeing within her the childlike innocence that had long been torn from his heart, Akechi quickly grows protective of Nanako, doing whatever he can to protect her innocence and shield her from the ugliness of the world.
As evident from the way she copies his mannerisms, Nanako clearly admires Akechi and looks up to him as a big brother figure. Akechi in turn adores her and treats her as the little sister he never had.
After taking care of him for a week and seeing his kindness towards Nanako, Dojima surprises Akechi by gifting him with a cell phone, indicating that he trusts him with his daughter's safety. This is what convinces him that Dojima is truly sincere about giving him a home.
Nanako then hugs Akechi and tells him how happy she is to have him around.
Knowing full well the difficulty of moving on from trauma, Dojima speaks with Akechi to ensure that he isn't feeling overwhelmed by their kindness. He then sympathizes with Akechi's past, refusing to pass judgment on either him or his mother, before telling Akechi something he needed to hear for a while.
Dojima: That father of yours is a piece of crap for leaving you behind. I might not know who he was, or why he walked out on you, but I'm not so blind as to ignore that you've had a… complicated relationship with dads.
Akechi: ...Masayoshi Shido. That is the man who ruined everything for her. Dojima: Shido… got it. [Sigh] I can't turn back the clock. Trust me, if I could, I'd do it in a heartbeat. But just so we're clear… That man isn't your dad. Damn bastard's a sperm donor at best, but he sure as hell isn't your parent. Akechi: [Holding back tears] No one has ever…
Knowing beyond a doubt that Dojima won't forsake him as his previous foster parents did, Akechi chooses to trust his new guardian, marking the start of their Social Link.
Akechi: [Kanji] did save me. …You as well, Dojima-san. You've given me more kindness these past few days than I've experienced in my entire life. But it feels so… unreal. This shouldn't be real. It can't be this simple… Dojima: It could be, if you let it. This is a fresh start for you, and I want you to feel safe here. Akechi: ...I do. You wouldn't lock the door and leave me to fend for myself in the rain. You wouldn't abandon me for your own convenience, because astonishingly, a child is more than an easy way to obtain state funding. You wouldn't have spoiled me so much in so little time if this was merely a means to an end… so I will choose to trust you, for now. Dojima: [Smiles warmly] Glad to hear it.
Upon reuniting with his uncle Dojima, Yu Narukami remarks that the former now has two kids under his belt, referring to both Nanako and Akechi. Soon afterwards, he refers to Dojima as "[Akechi's] dad", indicating that he already sees Akechi as part of the family. Given the emphasis Japanese culture places upon blood relations, its especially heartwarming to see that despite Akechi feeling threatened by Yu Narukami's presence, Yu himself has no problem seeing Akechi as family even though they're not related.
Akechi telling Nanako that she's The Heart of the household.
Nanako: The heart… that sounds really important. Akechi: It's very important. No matter what happens between me and Narukami-san, or how long your father works, you're the one constant we have to look forward to at the end of the day.
