[1]
Go here and Ryoma hears a woman scream. A group of thugs are telling her to hand over all the store's money or they'll kill her. Ryoma is about to step in to stop them, but then a samurai appears and he easily takes down the thugs. The woman thanks him, but screams when he turns around to look at her. She regains her composure, thanking him again, then leaving.
[2]
Talk to the samurai. Ryoma praises his skill in taking out the thugs. The man asks Ryoma if one's face really is so important. He explains that everyone he saves always freaks out when they see his face. Ryoma tells the samurai that one's appearance isn't what's important; one's character is. Suddenly, a woman passes by as notices the samurai and seems to recognise him. "Is that you, Aguri?". The samurai recognises the woman as well - her name is "Suzu". He asks her where he's going and she tells him she's heading to Kamo River to meet with a man called "Ikesugi", because he has something important to discuss with her, apparently. After she leaves, Aguri runs off after her. Ryoma thinks to himself he should check out what's going on as well.
[3]
When you get here, Ryoma sees the woman standing alone. It seems Ikesugi is late. Aguri is watching from the bridge and Ryoma goes up to him. Suddenly, Ikesugi shows up. He proposes to her! She says they haven't know each other that long and asks why he wants to marry her - He says because she's beautiful and wants to look at her forever. She rejects his marriage proposal, saying she doesn't care about appearance; she cares about personality. Ryoma tells Aguri that he still has a chance with her now. Aguri says it's not possible, with his appearance. He also points out that he doesn't want to risk ruining the relationship he has with her at the moment. You then have a choice of 3 things to say to him - choose the BOTTOM OPTION to say "Believe in Suzu". Ryoma points out that she says she cares about personality, not looks. Aguri says he'll go and talk to Suzu now. Ryoma notices Ikesugi is still by the river and he says "She won't get away with this!". He runs off to her, saying he's going to make her regret rejecting him.
[4]
Go here and Ryoma sees Aguri injured, with Ikesugi and some guys standing over him. They are about to kill him, but Ryoma steps in to save him. He tells Aguri to take Suzu and get out of here. A fight then starts against Ikesugi and his men.
After the fight, Ikesugi and Aguri have a stand-off, with Aguri saying he'll never forgive him for trying to hurt Suzu. After Aguri wins his duel against Ikesugi, he confesses his love to Suzu and she reciprocates. Aguri is surprised, pointing out that he's ugly. She again says that she cares about personality. Aguri thanks Ryoma for everything he's done and rewards him with a Gion Hood. You are also rewarded with 400 Dharma.
Also, after completing the substory, when you leave the area and come back into Mibu you will see Aguri sitting at the tea house. Speak to him to acquire him as a Super Rare Assist Soldier Card.