Yomogi Asanaka (麻中 蓬 Asanaka Yomogi) is one of the main characters of SSSS.DYNAZENON. A high school freshman who works part-time at Inamoto's shop, his life changes when he gets caught in the conflict with the Kaiju and becomes one of Dynazenon's pilots.
On the way to school, Yomogi and his friends see Yume Minami sitting atop a floodgate, and discussed various rumors they heard about her, particularly about how she breaks her promises. While on his way to work after school, he found Gauma collapsed underneath a bridge. He remarks that he is hungry and that something had happened to him, and Yomogi gave him his Special Dog, saving him from starvation. Gauma tried to talk to Yomogi more and grabbed his ankle, but he runs away to his part-time job. The next day, Gauma chased after Yomogi while he was on the way to school, wishing to repay him for his kindness, but his appearance and demeanor instead scared Yomogi away. Coincidentally, he ran up to Yume and after a brief conversation, they agreed to meet up later. However, Yume never showed up.
Gauma later appeared to Yomogi again and seeing that Yume was already forty minutes late, Gauma decided to go and find her. When he did, he confronted Yume about her broken promise with Yomogi, talking so loud that Yomogi could hear him. Before the conversation could end, Shalbandes appeared in the city. Gauma attempted to "capture" it using his Kaiju user powers but found that he was unable to. The object in Gauma's bag started to shine, and upon taking it out it summoned Dynazenon, who took in Gauma, Yomogi, Yume and Koyomi Yamanaka as its pilots. Gauma controlled the entire mecha by himself, despite it being his first time in it. After a tough battle, Dynazenon changed into Dynarex and finished off Shalbandes.
In the aftermath, Gauma passed Dynasoldier to Yomogi and told the him and the others to meet again the next day to begin their training, but Yomogi skipped out to go to work instead, even when Gauma went to his house to confront him about it. After reluctantly going off with Yume, the two of them got to know each other better and Yomogi learned about Yume's dead sister. Despite Yomogi's lack of training, the four pilots defeat Greyjhom when it appears. The Kaiju Eugenicists made their presence known to the Dynazenon pilots and called out Gauma as a traitor, putting a sense of distrust into the others. When the Kaiju Burnaddon appeared, they were unable to unite their hearts because of their distrust towards Gauma, but were able to do so once again after he told them the real reason he pilots Dynazenon - so that he can meet with the person who entrusted it to him.
Yomogi started to follow Yume around to investigate her sister Kano Minami's death. Eventually, they learned that Kano may have been bullied into suicide. Yomogi makes various attempts to help Yume through her period of depression and help her keep looking for more answers.
When he encountered Zaiohn, Yomogi managed to use Instance Domination on it after he and his friends imitate Gauma, who was trying to do the same. Yomogi and Knight look for the Kaiju together after it escapes from Gauma. Yomogi started to wonder if Kaiju had hearts, and Knight simply deflected the question when asked how he knew so much about Kaiju. Zaiohn later reappeared in giant size, forcing Gridknight and Yomogi to destroy it with the Dynamic Cannon, though before he was able to do so, Yomogi had hesitated as the Kaiju seemed to look directly at him.
After Garnix's defeat, life seemed to go back to normal as the Kaiju Eugenicists ran out of Kaiju seeds. After going around with Yume for a while, Yomogi confessed that he liked her and before Yume could say anything, they were ambushed by Sizumu, who revealed that he had been following them around to feed off their emotions. He tried to attack them but Gauma got in the way, almost getting killed. Sizumu then defeated Knight and unleashed Gagula to destroy the city. While Yomogi, Yume and the 2nd take care of Gauma, Knight fought Gagula as Kaiser Gridknight but lost. Yomogi and the others then went to retrieve their parts of Dynazenon to pilot together for the last time. Even with their teamwork, they were still being overwhelmed by Gagula until Yomogi used Instance Domination on it to force it to move its mouth up and provide the others with an opening to attack. While doing so, he had a conversation with Sizumu inside Gagula, where he was asked why he wanted to waste his powers as a Kaiju User and therefore his ability to free himself from the world. Yomogi stated that he would rather live as a normal human through the ups and downs of life along with the bonds he made with his friends. Sizumu is unable to comprehend him and leaves. With everyone's efforts, they manage to defeat Gagula and the Kaiju Eugenicists. However, Dynazenon loses its color and Gauma seemingly dies. Some time during the battle, the back of Yomogi's hand receives an "S" shaped scar.
Three months later, they visit the bridge where Gauma made his home before Knight and the 2nd leave with Dynarex and Goldburn. Yomogi is able to briefly sense Gauma's presence but dismisses it as nothing before going to school for a festival, where he dresses up as a mummy while Yume dresses up as a princess.
- Instance Domination (インスタンス・ドミネーション Insutansu Dominēshon): Yomogi is able to use Instance Domination, which allows him to connect to a Kaiju. His lack of training makes him unable to sustain the connection or control the Kaiju.
- Yomogi's parents divorced when he was in third grade, causing him to have to change his surname.