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VOICE No. 37


Katsuyoshi Michibayashi

Graduate School of Environmental Studies

My favorite saying: Lifelong study, lifelong youth


Q: Why did you choose this saying?

When I saw this saying written in calligraphy on a large piece of washi paper at the Mitsuo Aida Museum, I realized that these words were the very path that I should pursue. When I wrap up an interesting piece of research, I feel a sense of elation similar to what I felt when I was in my youth a long time ago. This saying spurs me on with the knowledge that always continuing my studies (research) is the only way to keep ahold of this feeling. There’s another similar saying that I also like: “Lifelong passion, lifelong youth”.


Q: What kind of research do you do?

I study the physicochemical feature known as rheology (the flow of matter), specifically that of the rocks and minerals that make up the crust and mantle of our planet Earth. If you were to compare the Earth to an egg, the crust would be the shell and the mantle would be the egg white. The crust covers the outer layer of the Earth, and the mantle is a layer of rock lying more than 6 kilometers beneath the crust. Humans have not yet reached the mantle, so we cannot directly touch it to study it.

As such, I look for traces of the mantle distributed in the Earth's outer layer, aiming to find mantle-derived rocks and minerals for my research. I have collected samples from various rock formations on land such as the Horoman peridotite complex at Mt. Apoi Geopark in Hokkaido, ophiolite rock formations in Oman in the Arabian Peninsula, and the peridotite xenoliths of the Australian continent, as well as from the depths of the ultra-deep seafloor, such as the Izu-Ogasawara Trench, the Mariana Trench, and the Tonga Trench.

So far, I have identified the makeup of the mantle flow in deep parts of transform faults and the mid-ocean ridge which creates oceanic plates. I have also identified the process of the mantle's structural development in the early stages of the formation of island arcs such as the Japanese archipelago.



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This rock is a treasured specimen of an olive-colored, mantle-derived

peridotite that was recovered from 9,731 meters deep in

the Tonga Trench by an American research vessel in 1996.  



Boarding the Shinkai 6500 submersible to investigate the

landward slope of the Izu-Ogasawara Trench (July 2017) 



Rocks recovered from the Moho transition zone (the boundary

between the crust and the mantle) 100 meters underground

during an international onshore drilling project in Oman, 

the Arabian Peninsula (December 24, 2017)



Q: How did you get into this research?

I’d been vaguely thinking about becoming a researcher ever since junior high school, but what made me enter my current field of research was a professor I had as an undergraduate student. He not only showed me the structures of rocks and minerals magnified under a petrographic microscope—which itself made a big impression on me—but he also taught me that we can understand rocks and minerals theoretically and quantitatively. These experiences moved me and to this day motivate me to conduct this research.



Q: You reached a depth of 9,801 meters at the bottom of the Izu-Ogasawara Trench, which is the deepest point in Japan's territorial waters, and thus broke a 60-year-old record for the deepest underwater exploration by a Japanese person. How did you feel when you reached the bottom?

We have conducted underwater explorations aboard the Shinkai 6500 submersible operated by the Japan Agency for Marine-Earth Science and Technology before, but, as its name implies, this submersible is only able to dive to 6,500 meters, which is the depth of the slope of the trench. I had always dreamed of one day reaching the bottom of the trench, and with this dive, my dream finally came true. However, I didn't have time or presence of mind to savor the moment—­I just kept exclaiming in astonishment, "I can see it! I can see it! I can see it!" I was honestly delighted that I was able to reach the almost flat, ultra-deep trench floor, not just the slope of it.




Dr. Michibayashi and world-renowned explorer Victor Vescovo shaking

hands on the submersible Limiting Factor just after reaching the

deepest point of the Izu-Ogasawara Trench, in celebration of setting

the Japanese record for the deepest submarine expedition

(photo courtesy of Caladan Oceanic and Inkfish)


Q: You must have faced many difficulties to reach the bottom of the trench. What was the most difficult part?

Deep-sea expeditions of the ocean floor are dependent on weather conditions, so it is quite common for them to not proceed as planned. Given that, we didn’t let our hopes get too high while we were at sea; we knew there was a chance that the expedition itself might be cancelled. This time our expedition went as planned, but right up until the day of the dive, I was seasick and wasn’t able to do much of the onboard operations. That may have been the hardest part for me. In order to be in perfect physical condition for the day of the dive, I did everything I could to recover from my bout of seasickness. Luckily, the weather was nice on the day of, and I was able to take part in the dive in perfect health. After the dive, I felt weak and got very seasick again.


Q: How do you spend your days off? What do you do to recharge?

On my days off, when the weather is good, I ride my road bike to the tip of the Chita Peninsula to eat kaisendon, a bowl of rice topped with sashimi. On rare occasions, I travel to Lake Biwa or Ise-Shima by train and bring my bike with me to ride there. When I’m out biking, I'm busy paying attention to my surroundings and checking stats like my heart rate and my speed and cadence on my bike computer. Using my brain like this, in a way that’s different to how I usually do, is one way I relax and recharge. The feeling of accomplishment I get after completing a 150-km bike ride and checking my cycling route on a map afterwards is truly special.

On days when the weather is bad, I read novels and manga or watch movies and TV shows at home.



Cycling around Lake Biwa (July 2021)


Q: Give us the inside scoop. Do you have any stories that you can only share with us now?

When I first started working at Nagoya University, I thought to myself that so many of my fellow professors and students were from the greater Nagoya area. But then I realized that my own hometown, Sakuma-cho in Shizuoka Prefecture, which is part of the Oku-Mikawa area, is not that far from Nagoya. No one pointed it out to me or anything, but I still felt a little embarrassed when I realized that. I rediscovered myself as someone who eats miso soup made from red miso paste without hesitation.


Q: What are your goals and ambitions for the future?

I am a professor of the Rock and Mineral Laboratory, known as Ganko, which is a lab with a long tradition of producing many graduates who play an active role in society. Research topics related to rocks and minerals may change with the times, but I will continue researching and teaching in a fun and sometimes strict way with “lifelong study, lifelong youth” as my motto, with the goal of making rocks and minerals the focus of Japan and the world and educational activities with our students in a fun and sometimes rigorous manner. With the motto "Lifelong study, lifelong youth," I aim to make the Rock and Mineral Laboratory the center of Japan and the world. And, if I get the chance, next I would like to explore the Challenger Deep (10,927 meters deep), the deepest part of the Mariana Trench, to collect mantle-derived rocks.




Climbing Mt. Happo-One in Nagano Prefecture with students of

the Rock and Mineral Laboratory (October 2021)


Name: Katsuyoshi Michibayashi

Department: Graduate School of Environmental Studies, Nagoya University

Title: Professor


Dr. Katsuyoshi Michibayashi graduated from the Department of Geosciences, Faculty of Science at Shizuoka University and then went on to complete his Master's at its Graduate School of Science. He completed his doctoral studies at the Graduate School of James Cook University in Australia, earning a Ph.D. He became a professor and research fellow at the Faculty of Science at Shizuoka University before attaining his current position at Nagoya University in 2018. He is also a visiting researcher at the Japan Agency for Marine-Earth Science and Technology.

His hobbies include road cycling, taking landscape photos, reading books (including manga), and watching movies, TV shows, anime, and YouTube .