Per wiki policy, Spoilers Off applies here and all spoilers are unmarked. Tread carefully.
The entirety of Yagami and Kaito's relationship. They may butt heads at times, but you can tell they both have the utmost faith in each other and stick together through thick and thin. This friendship is only reinforced further by the conclusion to the side case "Partners". After Yagami spends most of the side case trying to warn Kaito that his old childhood friend Adachi has become an incredibly corrupt real-estate agent, the two of them end up coming to blows. Yagami is outright hurt that they had to fight, believing that he doesn't have a way of communicating with Kaito. Except it turns out that Kaito already suspected Adachi's true nature from the beginning and just wanted to confirm it for himself. After sending Adachi packing, Kaito dismisses his old friendship with Adachi, saying that he already has a partner in Yagami. The case concludes with the two of them affirming their partnership with a light fist-bump.
The scene where Yagami goes to meet Okubo after learning that Yoji Shono was most likely the true culprit in Emi Terasawa's murder. He tells Okubo that he truly believes he's innocent now, and he'll do his best to avenge Emi's death. Yagami then apologizes for refusing to believe in Okubo, and begs for forgiveness with tears in his eyes. Okubo, at this point a broken man who has been serving over three years on death row, waiting for his execution because of Yagami, begins tearing up as well, and says that he not only forgives Yagami, but feels he should be the one begging for forgiveness in this situation.
Sugiura forgiving Okubo after the revelations that Sugiura is Emi's younger brother and Okubo is innocent.
After the first fight with Kuroiwa, Yagami exits L'Amant to find Higashi and Kengo leading the remnants of the Matsugane family in threatening to cause a riot unless Yagami is released unharmed. After the yakuza see that Yagami is unharmed, they disperse, revealing that Hoshino of all people was among them. Yagami then sees Mafuyu, Genda, and Saori in the distance looking at him with approval.
The Side Case "Revenge of the Keihin Gang" requires Yagami to make Friends with everyone possible in the game before it can be taken, and for good reason. The case involves Yagami having a price of ten million yen put on his head by the Keihin Gang and finds himself dodging multiple members of the local population after that reward, from street punks to old men with bats to small children. While Yagami attempts to solve the case, at multiple points the Friends he's made show up to lend him aid, from the fighters, to the business owners, and even the hostesses join in to distract the mob. At the end of it all, Yagami gives all his friends a heartfelt thanks and can even visit everyone individually to thank them.
The "Circle of Law" side case where Genda steps in and helps the daughter involved in a divorce speak up that she wants her family to stay together.
The entirety of the side case, "Secrets of Cats".
Many of the Friend Events you do can end up like this. Playing matchmaker to a pair of baristas, helping a student make enough money so she won't have to work a sex job, befriending a doctor who helps the homeless, the list goes on.
When Yagami, Kaito, Higashi, and Sugiura are forced to leave Ayabe's trial to stop Kuroiwa and Shono from being murdered by Ichinose, Yagami leaves Hoshino to take over. Despite Hoshino's initial panic, he manages to find his resolve when Saori gives him a smile to cheer him on. This simple gesture is enough to give Hoshino the confidence to continue with the trial.
