@clematis nice point! I totally forgot that he doesn't have money lol. But seeing how he's in a gang and Mikey probably knows people, they could probably find someone with money to invest by proving to them that he has abilities. His parents wouldn't trust a 14 year old, but they would trust a 14 year old with proof that he's a time traveler lol. The bigger point here is that he can easily prove that he can time travel (
please see the example at the bottom of this comment) with a minimum amount of effort, and get anyone to trust him and follow his lead. I didn't realize it until you said it, but yeah Kisaki is actually doing a wayyy better job at utilizing his time travel powers than the MC is! He easily became the leader of this huge enemy gang and recruited a ton of powerful members. Meanwhile the MC is just struggling to be a captain of just one squad inside Touman and keep everyone alive.
MC method: just focuses on one event (when X is going to do something or when X is going to die, I will stop it so that future events will change)
Kisaki method: I am a freaking time traveler so let me just use my powers to get information on everybody and manipulate them so I can literally make my own gang that's stronger than Touman
If the MC actually used his powers instead of just playing a role as a normal non-superhuman gang member, he would easily beat Kisaki and make Touman overpowered.
In-Depth example: Get a list of significant events that occur within a week and a list of stock prices at the end of the week. Give this list over to people with money (people Mikey might know, or honestly he could just show his parents). Within a week, every single event on that list will occur along with stock prices having an exact match. He now has the trust of those people and they believe that he can tell the future. He can then make some agreements to take a 50% cut (even something like 20% would be enough) and invest in stocks that will get a 10x or even 50x return within the month (there are almost always random unknown stocks that rise tremendously ever week, which they can buy and sell at the peak point before it dips). These huge profits and connections would basically make him one of the most powerful people in Japan, and with money he can protect Touman and recruit way more people as well.