Haruku Umemura (Plumvery)
Portfolio 2025

I build games and tools that help people connect—and feel like they belong.

Haruku Umemura (Plumvery), b. 2003 — from Gifu, Japan.

It was in the third grade when I was suddenly struck by an unstoppable urge: "I have to make a game." I immediately searched "how to make games" on the school library PC. Discovering something called "RPG Maker," I scoured multiple used game shops that very day until I finally found a copy of "RPG Maker DS."
From then on, pushing my homework aside, I poured myself into game creation. However, I soon found the DS version too limiting. I moved on to a free software called "WOLF RPG Editor" on my family's old Windows XP computer. But even then, the features of free software couldn't satisfy my hunger.
In the fourth grade, I challenged myself to build 3D games using C and DxLib. By the time I was in the fifth or sixth grade (around 2015), I had started using Unity 4 and Unreal Engine 4, which had just become free to use.
My life had completely shifted from "playing" games to "creating" them. But for an elementary student in the countryside, this was also a battle against isolation. I had no friends who spoke my language.
By junior high, the desire for "companions" drove me. I traveled all the way from Gifu to Osaka for game jams, and in my third year, I made it to the finals of the "Unity Inter-High" (an official national competition for high schoolers), which took me to Tokyo.
It was there that I first met "peers I could speak with passionately." That encounter made me determined to move to Tokyo in the future.
Then came 2020.
The COVID-19 pandemic began. The world shut down.
As a high school sophomore, I was completely cut off from visiting Tokyo.
The physical connection with the friends I had finally found was severed, and I suffered from intense loneliness.
That was when it hit me: "If we can't meet, I'll build a place myself where we can show our work and build games together—as if we were sitting right next to each other."
That sheer determination is what birthed "KillinEngine," a game production tool that allows for real-time collaborative editing over a network.
While developing "KillinEngine," I was certified as a Super Creator under the Mitou Junior 2021 program. After raising capital, I founded Killinzy Inc. and, fulfilling my long-held dream, started my new challenge in Tokyo in 2024.
What I want to create is not just games or tools.
It is a "place to belong"—a place where people can connect, find their roles, and share their enthusiasm through creation, just like the sanctuary I yearned for when I was alone facing my PC.
To achieve this, I believe it is essential to keep sharpening my skills and technology as my weapon.

I work on projects involving emerging game platforms.

I work on planning, development, and live operations in the space of emerging game platforms. With a focus on online multiplayer experiences and systems that help gameplay spread organically, I want to take projects end-to-end—from rapid prototyping to implementation and continuous iteration.

What I do best: Online multiplayer game development

I plan, design, and develop online multiplayer games using real-time networking.
I believe early playtesting is everything—so I prototype fast, test often with users and the community, and iterate based on what we learn.
My main tools are Unity (including WebGL), Unreal Engine 5, and Minecraft.

Next focus: Digital twins with 3D graphics / CAD / BIM

My family runs a construction business in Japan, so I’ve been curious about digital twins for cities, infrastructure, and building workflows for a long time.
Up to now I’ve mainly focused on software; going forward, I’m exploring projects that connect real-time 3D (game engines + 3D assets) with the physical world.

July 2024 – Present: Freelance Unity developer

I support online multiplayer development in Unity, rapid prototyping, and Minecraft-based multiplayer experiences for creators. I’ve also built a LINE Mini App from scratch (LINE is a major messaging app in Japan) and supported Steam game development using Unity/UE5.

Jun 2023 – Dec 2023: Organized Unity New Generations Fest (UNGF) (Japan student/community event)

After Unity Japan announced the cancellation of “Unity Cup” (Japan student contest series), we formed an organizing team led by alumni and community members.

With sponsorship from multiple companies, we hosted “Unity New Generations Fest (UNGF2023)” on December 3, 2023, at the N/S High School Yoyogi Campus (Tokyo campus of a Japanese online high school group).

Sep 2022 – Mar 2023: Built and delivered games for Mementori live events (Japanese creator group)

I created and delivered an original game used as part of a live show for “Mementori,” a popular gaming creator group (500k+ subscribers) active mainly on YouTube.

Apr 2022 – Present: Meiji University (Tokyo, Japan) (Interdisciplinary Mathematical Sciences)

I studied foundational HCI and computer science.
Since April 2024, I’ve been on leave to focus on work.

Mar 2022 – Jun 2024: Founded Killinzy Inc. (CEO)

I founded Killinzy to commercialize KillinEngine.
We raised a total of ¥26M in pre-seed funding (lead: Primal Capital (venture capital)) and worked from Hive Shibuya (startup co-working/incubation space in Shibuya, Tokyo).

Jan 2020 – Feb 2022: Built KillinEngine

I built KillinEngine, a multiplayer game development tool that enables real-time collaboration for remote teams using online networking. It was selected for Mitou Junior 2021 and received “Super Creator” recognition.

Jan 2019 – Dec 2019: Built “Asa wo Shiranu Hoshi” (A Star That Never Knows Morning)

With my 3D game “Asa wo Shiranu Hoshi,” built in my first year of high school, I reached the finals of Unity Inter-High 2019 and the Japan Game Awards U18 2019 (Japan Game Awards: under-18 category). The game was showcased at Tokyo Game Show 2019 (major game expo in Tokyo) and received multiple awards.

Apr 2019 – Mar 2022: N High School (Japanese online high school) (online program)

Graduated in 2021 and received a special commendation.

Apr 2018 – Dec 2018: Built “Otenba Shojo to Gakko no Meikyu” (Tomboy Girl and the School Labyrinth)

While showcasing my solo 3D game at a local indie event (“Zentame”) (local creator event in Japan), I was interviewed by Famitsu. The game also reached the finals of Unity Inter-High 2018 and won a Special Jury Prize.

Apr 2017 – Mar 2018: Co-led Asterisk Lab

I co-led Asterisk Lab, a small technical research team and blog, with Sakamoto (a freelance 3D artist). We published technical articles and essays.
One of our UE4 character pipeline articles was featured in CGWORLD magazine (Japanese CG industry magazine) (Jan 2018 issue).

Around 2016 – 2017: Joined Unreal Engine game jams in Osaka, Japan

I traveled from Gifu to Osaka to join Epic Games’ official game jam events, stayed overnight, and learned what it takes to build as a team under tight deadlines.

Around 2014: Started making games with RPG Maker and Wolf RPG Editor

I discovered RPG Maker at my school library, hunted down a copy of RPG Maker DS at secondhand shops, and got completely absorbed. (It was the Nintendo 3DS era, so DS software was already disappearing from store shelves.)

Aug 12, 2003: Born in Gifu, Japan

I was born with esotropia (a type of strabismus) and have worn glasses since I was little.

Aliases

I’ve used the handles ぷら虫 / プラムベリー / plumvery.

Social

• Haruku Umemura (@plum_very) / X
• Haruku Umemura / Facebook
• plumvery_jp (Haruku Umemura) / GitHub
• Haruku Umemura / LinkedIn

Contact

For work inquiries, collaborations, or questions, email me at:
[email protected]