The two never interacted on-screen, as they were from different games. However, they share an event together in Danganronpa V3's bonus mode, Ultimate Talent Development Plan.
In the event, Ishimaru is a member of the morals committee. Soda is trying to walk in the hallway unnoticed, as he is wearing a very messy outfit. But while he is trying to sneak away, Ishimaru catches him. He then tells Soda that he stuck out with his messy face. He tells him that he won't let him get way today, meaning that he has escaped before. He then tells him that the outfit he is wearing is disturbing public morals. Soda tells him to leave his outfit alone, but Ishimaru told him that that would be abandoning his duty as a member of the morals committee. Soda tries to come up with a plan to get him to listen, so he tells him that since he's a mechanic, he has to wear his uniform so he can do his jod any where. Ishimaru says that that is a good point to consider, but that it's no reason for the uniform to be so messy and garish.
Soda then gets stressed at the fact that he didn’t buy it. Ishimaru told him that he wouldn’t be deceived and that he wasn't a fool. Soda asks him if the way he dressed really mattered. Ishimaru tells him that it is very important. He says that disorder in someone’s oufit is a disorder in their heart. Soda tells him that he understands and that people wouldn’t treat a nerd and a guy like him the same way. Ishimaru asks Soda which one would he trust more. Soda describes Ishimaru and tells him that he's sure everyone would think that Ishimaru would be more responsible.
Ishimaru is shocked at the fact that he knows and asks him why he hasn’t fixed his appearance and if he's ok with people not liking him. Soda tells him that looking like this is fun to him. He then tells Ishimaru that he would get more girls than a nerd like he would. Ishimaru got a little on edge from that and asked him what he meant. But class is about to start so Soda goes off. Ishimaru yells for him to stop disturbing the morals.
- Soda – “...Aw shit!”
- Ishimaru – “Hm? Hey! Where do you think you're going!?”
- Soda – “I-I've been caught!”
- Ishimaru – “Of course! You stick out with that garish face of yours! I won't let you get away today! A man like you with such a garish outfit from top to bottom...you're disturbing public morals!”
- — Ishimaru catching Soda in his messy outfit.
- Soda – “Gaaah! Shut up! Leave my outfit alone!”
- Ishimaru – “Leave it alone!? I'm a member of the morals committee! That would be abandoning my duty!”
- Soda – “Alright, hold on a sec, Taka! Think about it... I'm a mechanic yeah? So this outfit's my uniform! It's so that I can do my job as a mechanic any time I need to!”
- Ishimaru – “Hmm...that is an important view to consider.”
- Soda – “Right!?”
- Ishimaru – “But that's no reason for your uniform to be so garish! Not to mention your whole head!”
- — Soda trying to convince Ishimaru to leave him alone.
- Soda – “Y-You didn't buy it...”
- Ishimaru – “I will not be deceived! What kind of fool do you take me for!?”
- Soda – “Whoa, wait, wait! Hold on, Taka! Is the way I dress really that important?”
- Ishimaru – “Of course it's important! Disorder in one's outfit is disorder in their heart!”
- Soda – “...I see. Nah...I get it. The way you look is important. For example, a plain nerd and someone who looks sleazy like me...People wouldn't treat them the same.”
- — Soda understands Ishimaru's reasoning.
- Soda – “More importantly...doesn't it seem like I'd get a lot more chicks than a nerd like you!?”
- Ishimaru – “Wha—!? What are you saying!?”
- Soda – “Whoa, looks like class is about to start! Hehe...see ya!”
- Ishimaru – “Y...You're disturbing public morals after all! Hold on, Kazuichi! Kaaazuuuiiichiii!”
- — Soda tells Ishimaru he can get more girls than he can.
Soutaka is one of the many ships that sailed as a result of the interactions between characters in Danganronpa V3's bonus mode, Ultimate Talent Development Plan. It gained its popularity because of the two's many differences. Soda being a disobedient messy student, while Ishimaru is a responsible clean student. There opposite personalities make them a good match for each other. Thought Ishimaru was getting on his nerves, he seemed to be have a little fun with him at the end of their interaction. A lot of people also ship the two with Mondo Owada.
Nonetheless, because they only interact with each other in the Ultimate Talent Development Plan, only a small part of the community actually ship the two together. Additionally, both characters have their much more popular ships from the canon. With Soda having Soudam and Sounia, and Ishimaru having Ishimondo and Ishikuro. In spite of this, the ship has a fair number of people who have made fanart for this ship.