Ayame Yomogawa (四方川 菖蒲 Yomogawa Ayame) is the eldest daughter and heir of the Yomogawa family that governs Aragane Station who is the user of the master key.
Ayame has a very mature and soft-spoken personality who is shown to be quite obedient and dependent on Kenshou Yomogawa (Ayame's father), such as when she refused to board the Koutetsujou until her father has given her the signal.
As a leader, she cares deeply for her people but very passively in action and decision. However, as the story progresses, Ayame is shown to slowly step into her role as the leader of the group.
Ayame was first seen in Argame station with Kenshou Yomogawa (Ayame's father) and his bodyguards when she she came to have her father's steam gun repaired. She was surprised when Ikoma asked her as to where she will be pointing the steam gun. When the Koutetsujou arrived earlier in the station, She was visibly worried when her father informed her that another station might have been overrun by kabanes. When her father ordered the bushi to arrest Ikoma for defending a suspected kabane, she tried to stop him for being unreasonable. Her father dismissed her explaining that maintaining order is the bushi's duty. After the west gate has breached, her father went to the Koutetsujou while he ordered her to remain and wait for his signal. Still waiting for the signal, she refused to go to the Koutetsujou until Mumei cleared a path for them to follow.
At the Koutetsujou she maintained order while the people board the hayajiro. In the crew compartment, she was surprised when Mumei arrived and criticized her of her leadership. She is later horrified when she saw her father as a kabane as the koutetsujou cruised past, killing him. When Ikoma and Mumei were revealed to be kabaneris, Ayame defended them despite the persistence of those all on board, thanking them for saving the koutetsujou. She later held a vigil for everyone when the water tank of koutetsujou was being repaired.Ayame was bewildered when a group of worried people were sneaking in to kill Mumei and Ikoma. To prove that they were on their side, she tried to provoke Ikoma into biting her. Rather than bite her, Ikoma vowed to never run again, and explained that the purpose of his life is to destroy the kabane. Seemingly convinced, the people started walking away. She later apologized to Ikoma for the incident. As she was about to leave, Ikoma suddenly collapsed from blood starvation and she started ripping her dress to make a bandage, as she thought Ikoma had passed out from blood loss. He tried to attack her, and she was close to being bitten when Kurusu came in and stopped Ikoma. As the koutetsujou advanced due to the approaching kabanes, she was later dismissed to take control of the koutetsujou.
Under new leadership (the Six Chiefs), they head for the mountain, which is a faster route but more vulnerable to attacks. As they head into a tunnel, they were ambushed by kabanes and among them was a wazatori. Ayame decided to join Kurusu and the others to fight the kabanes, which confused everyone. She watched helplessly as one of her bodyguard got bitten and more kabanes kept coming. She was terrified when the wazatori came and injured Kurusu. Much to her relief she heard Ikoma promising to take down the wazatori if someone would give him blood.Determined, she cut her forearm to let her blood flow, and forms a contract with Ikoma to drink her blood in exchange for his aid in killing the wazatori. Ikoma gladly accepts and as he drinks, the blood starts to pour in his heart, which starts to beat. Exhilarated, Ikoma pinned the wazatori down and pierced its heart with his steam gun. Ayame regained control of the koutetsujou and with her in command she declares that Mumei and Ikoma will travel with them and volunteered to offer her blood along with Takumi, Kurusu and the others as well.
After the train is unable to move further, Ayame was present at the gathering where Ikoma proposed a plan to move the tower that fell onto the road, agreeing with his plan.
Shitori Station Arc
Upon arriving at Shitori Station, Ayame tells the chiefs to watch over the Koutetsujou, as she attends to her duties. When the group remembers that it is Tanabata, she provides a valuable box for Ikoma and the rest of the group to use as money, so they can celebrate the event. Ayame, along with Kurusu and Kibito, go to meet with the lord of the station. While waiting outside the meeting room, Kurusu and Kibito discuss how the lord is late and wonder if it is due to the reason that food is scarce at the time or the lord's unwillingness to negotiate. Kurusu decides to go talk to Ayame but discovers her indulging in the food that was offered to her. Ayame becomes immediately embarrassed at being seen stuffing food into her mouth, while Kurusu, who is shocked and flustered, apologizes for intruding and shuts the door. He tells Kibito that they should wait a little longer. As the minister of Shitori Station, Yamazaki, and two servants are passing by, Kurusu fires a shot into the air, alerting them to their presence. Ayame introduces herself and offers jet bullets as a gift for Lord Shitori. Kurusu demonstrates the potency of the bullets by firing a shot at a iron plate. Yamazaki and his followers are amazed at the sheer power, assessing how the jet bullets could penetrate a Kabane's heart cage. Ayame also says how she is willing to include blueprints of the bullets if they are interested, since she believes it's only natural to help others in times of need. Her sweet charm wins over Yamazaki, and he promises to give her food provisions and take in the sick and injured in her group. During the Tanabata celebration aboard the Koutetsujou, Ayame divulges to the group that her wish is to reopen Aragane Station, making people laugh, which causes her wonder if her wish was strange. Kurusu smiles and tells her that her father would be proud of her wish to Ayame's delight. When Ayame questions about Kurusu about his wish, he blushes and becomes embarrassed, hiding his paper behind his back and stating that his wish won't come true if other people see it. Ayame watches the fireworks of Shitori Station alongside the rest of the crew.
Ayame is shown to be skilled with a bow and arrow. She wields a large and heavy bow which have some similarities to a steam gun, with a spring attached to it so her arrows are shot much more quickly and with much greater force.
When the Koutetsujou was ambushed by Kabanes she was able to provide resistance by shooting them directly into their hearts. Ayame managed to kill a Kabane with a single arrow which pierced it's heart cage.
Ayame trusts Ikoma almost naively. Even when most passengers were uneasy about having Kabaneri on the Koutetsujou, she kept her faith on Ikoma, knowing that he has good intentions. After Ikoma tried to attack her, she offers him her blood in exchange that he will fight for them and defeat the Wazatori.
As her bodyguard, Ayame has good faith in Kurusu. After Kenshou Yomogawa's (Ayame's father) death, she depended on Kurusu's protection on their journey to Kongoukaku. Kurusu is shown to let down his stoic demeanor when he is around Ayame. He is also quick to come to the defense of Ayame, especially if people question her authority or decisions. Kurusu appears to have feelings for Ayame.
- The name Ayame means "iris (flower)" (菖蒲).
- Ayame's surname Yomogawa means "four" (四) (yo), "direction" (方) (mo) and "river, stream" (川) (gawa).