This is Hamamoto from TIMEWELL Inc.
What Leadership Actually Looks Like — and Where Side Work Fits In
When people hear "leadership," the image that comes to mind is often forceful — a person who drives others forward. Taisei Mizuno has led teams in various forms since middle school. But what shaped his actual leadership style, he'll tell you, was a year of failure and self-examination during his ronin period before university. This interview covers his path from student leader to full-time project manager to AI engineer side-jobber — and what each of those contexts has taught him.
Title: Senior AI Engineer, Technology Division — TIMEWELL Inc. (side role) / Project Manager, System Development Division — NTT West (primary role)
Background: Originally from Shizuoka Prefecture. Joined NTT West in 2021 as a new graduate. Worked on business process reform and work environment transformation project management. Active member of "NTT-WEST Youth," a voluntary internal organization that hosts cross-boundary events within NTT. Connected to TIMEWELL through a side-work recruitment event in August 2023.
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From Class Representative to AI Engineer: The Through-Line
— Let's start with an introduction.
I'm in my second year with TIMEWELL. My main work here is running TIMEWELL MEDIA — making sure the tech-related content stays substantive — and developing AI-powered applications, both for internal efficiency and for clients.
My primary job is at NTT West, where I work as a project manager on system development — evaluating new system implementations and leading the operational reforms that go with them.
— You had significant leadership experience as a student. Can you walk through it?
In middle school and high school, I served as class representative and as captain of the soccer team. I took on those roles partly because I was put there by teachers first, and then I found that I actually liked pulling people together. Standing in front of a group and moving things forward felt natural to me.
At university, I led as a part-time work team leader. The thread through all of it: put the team first. Leadership isn't about commanding from the front — it's about understanding what each person needs and creating conditions for them to do their best.
— You have a noticeably calm presence. Where does that come from?
I don't think I'd have identified that about myself, but reflecting on it — my ronin year was the turning point.
I didn't study effectively in high school and failed my university entrance exams. Spending a year studying again, without a team around me, forced me to understand what learning actually is and to look at myself honestly. That experience built the habit of seeing things from a step back — including myself. When you've been through a period of genuine failure and worked your way through it, you develop a reference point. Problems don't feel as permanent.
Leadership reinforced that. When you're responsible for a team, you learn to observe people, read situations carefully, and keep your reactions measured. The combination — ronin year plus years of leading teams — is probably what people are picking up on.
The Side Job Decision: What Didn't Fit and What Did
— What made you decide to pursue side work at TIMEWELL?
In my second year at NTT West, I applied for a transfer to a subsidiary that was doing new business work. I was rejected — the feedback was that I didn't have new business experience. It created a circular problem: I couldn't get the experience because I didn't have it.
My response was to get that experience through a side job. I started actively looking for new business environments where I could contribute and learn.
Then, coincidentally, an NTT Group side-work recruitment event happened. About ten companies participated. Hamamoto from TIMEWELL was one of the people presenting, and his energy and genuine enthusiasm stood out clearly from the rest. I applied, had a follow-up one-on-one conversation, and felt more strongly that this was where I wanted to be. I was brought on, filed the necessary paperwork with NTT West, and started.
— You're now in two very different professional communities simultaneously. What does that give you?
I've heard the idea that belonging to three or more communities raises personal happiness levels — and my experience aligns with that.
Before I started side work, when something went wrong at my main job, it would stay with me. I'd think about it late at night, carry it into the next day. Now, if something fails in one context, I can shift to the other — contribute there, get my footing back, and approach the original problem from a cleaner headspace. The communities buffer each other.
The mental stability I've built from belonging to multiple places is one of the most concrete things I've gotten from side work. It's changed how I process setbacks.
What TIMEWELL Offers That Large Companies Don't
— What gives you the most satisfaction in the work here?
The autonomy and the speed. At TIMEWELL, I have real decision-making responsibility within my scope — I'm not waiting for three layers of approval to try something. That makes it possible to actually respond to what's happening, and to see the direct result of decisions I made.
At NTT West, decisions that should take a week can take months. I understand why large organizations work that way — risk management, scale, stakeholder alignment. But it's not motivating. At TIMEWELL, the startup pace isn't stressful — it's energizing. When you can move from idea to implementation inside the same week, the feedback loop is fast enough to learn from.
I also try to compensate for the fact that having autonomy can create a top-down dynamic unintentionally. I make a point of working harder than I ask others to work. If I'm asking the team to do something, they should see me doing it too.
— What have you taken away from the experience so far?
Understanding the difference between how large and small organizations actually function — not theoretically, but in practice, in your body. I know what it feels like when decisions move fast versus slow. I know what it costs each way.
The startup experience also builds a kind of credential: I've been involved in early-stage work, which is something I couldn't point to before. That matters for the direction I want to move in.
— What are you aiming for going forward?
Contributing to TIMEWELL's growth is the clearest near-term goal — through MEDIA operations and application development. There are people at TIMEWELL with far more experience than me in many domains, and I'm still learning from all of them.
The longer-term picture: I want to build enough experience here that it loops back to benefit my primary work. That reciprocal growth is the reason side work is worth doing.
— Any message for readers who are thinking about this?
If you're interested in side work, the most important thing is to start. You don't know how it will go — there will be failures. But challenge is how the path opens. Start from what you can actually do, do a bit more each time, and your range expands. Failure isn't permanent; it's the mechanism.
Taisei Mizuno's story is one of using the constraints of a large organization as motivation rather than limitation — and finding, through that process, a working life that is genuinely larger than either role alone.
Learn more about TIMEWELL's services and working opportunities on our website.