Curate, connect, and discover
Talking more on the theme of delusion, Matakara relies on it as an escape from his sensitive emotional nature. Since childhood he's been susceptable to these dark thoughts, which his brother (and presumably kid Arajin) helped him deal with. Now, without his brother, the ideal of Arajin he cultivated since childhood, the one who believed in becoming a Honki person with him, is the main thing able to distract him from his painful reality. He was writing a letter to his brother the first time one of the shadows appeared in the series and he proceeded to pick up the stone stamp in order to calm himself. After Arajin rebuffed him when he asked him to call off the gang war, other shadows appeared and he needed to rely on the connection with his brother in order to find strength and later appeal to Mahoro. As he is now, he needs some kind of ideal or delusion to be able to keep functioning.