I attended RubyKaigi 2026
I attended RubyKaigi 2026. I am still not sure where to start. The technical talks, reunions with people, and time in Hakodate with my family all feel like separate topics, but they were loosely connected within the same few days.
What I felt most strongly at RubyKaigi this year was that many things are moving. Ruby itself is changing, the technical environment around Ruby is changing, and my relationship with the community is changing too. The fact that going to RubyKaigi with my family is gradually becoming an annual event for us may be one part of that.
Talks that made me feel Ruby changing
Since this is an article about RubyKaigi, I will start with the technical talks.
Matz’s keynote stayed with me. While listening, I imagined many things that might have been going through his mind. But what stayed with me most was the feeling that I wanted to actually try Spinel. After I got home, I tried it right away and wrote an article.
After that, I noticed that likes were suddenly increasing. When I opened Twitter, I saw that Matz had tweeted about it. I was honestly happy.
Matz’s tweet
What made me even happier was that a former teammate, someone I reunite with at RubyKaigi, reposted it.
The first time I attended RubyKaigi was in 2018. That teammate had attended in 2017 and recommended it to me. At the time, I could barely understand the technical talks. Still, I have been building things little by little, and while listening to the talks this time, I felt that accumulation, if only a little. At the same time, I also felt that the ground I stand on is itself moving in a big way.
Another talk that especially stayed with me was Koichi Sasada’s The AST Galaxy to the Virtual Machine Blues.
It introduced ASTro, an AST-based Optimization Framework. What I personally found interesting was that Merkle trees were used. I have touched Merkle trees a little in the context of blockchain. For example, they are used to calculate allowlists for airdrops and reduce gas costs. It was interesting to see that technique appear in Ruby optimization.
It also stayed with me that Sasada-san was presenting not about Ractor, but about a new technology. Listening to Matz’s talk and Sasada-san’s talk, RubyKaigi this year became a place where I could feel that Ruby is about to change in a major way.
RubyKaigi as a company event
RubyKaigi has now become an event attended by all server-side engineers at my company. This year, some members also participated by giving LT talks. When I think about the effort behind that, something wells up.
I was thinking about that during the opening party too. But I could not put it into words very well. Maybe that is fine. There is probably meaning in leaving some feelings as they are, before they become words.
A technical conference is a place to learn technology, but it is also a place to see how people change. I reunite with people I once worked with, see the challenges taken on by people I work with now, and notice changes in myself. RubyKaigi has become that kind of time for me.
Walking around Hakodate with my family
From here, I will write about things outside the Kaigi.
There was a member I had planned to reunite with in Hakodate, but this time we could not meet. We exchanged a few emails, and they told me, “Please make sure to see the night view of Hakodate.”
Actually, we had planned to go to Mount Hakodate on the first day. But our flight was delayed, and we had to reconsider the schedule. Since I was attending with my family again this time, the delay caused a bit of a scene.
Personally, there was a good part too, because the delay gave me time at the airport to talk by chance with Shioi-san, a Rubyist. But my child was quite angry at first.
There were several announcements about the flight delay. I told my child each time, but I think I handled the communication badly. It ended up becoming a repeated cycle of raising expectations and then postponing things again. My child’s anger gradually reached its limit, and eventually they started crying.
That was when I realized something. My child’s anger was the flip side of how much they had been looking forward to the Hakodate trip. I reflected a little on myself for trying to persuade them by saying they were getting too angry. The desire to enjoy the trip was probably much purer.
We were able to board the plane several hours late. Once my child could watch Zootopia 2 on the plane, their mood recovered all at once.
So we were supposed to miss the night view of Hakodate, but because of that email, we adjusted the schedule on the second day and went to Mount Hakodate. It was crowded and a little tiring, but the night view was very beautiful. We went up the mountain around dusk, and while watching the color of the sky change and the lights of the city gradually increase, I thought about many things.
Night view from Mount Hakodate
The beauty of natural colors. The everyday life of people contained in each light. I watched those things in a vague, quiet way.
Dusk on Mount Hakodate
Cherry blossoms at Goryokaku
On the final day, we went to see the cherry blossoms at Goryokaku. It was near our hotel, so we had seen them little by little before then, but on this day we set aside more time.
One of the things I wanted to see in Hakodate was the cherry blossoms at Goryokaku. I am not especially knowledgeable about the Shinsengumi or the history of Goryokaku. Still, I sometimes think about how people lived through the upheaval of the Meiji Restoration. If I saw the cherry blossoms at Goryokaku, would something change inside me? I wanted to find that out a little.
The children also seemed to become a little interested in history. I wonder if someday they will learn through writers like Ryotaro Shiba. If possible, I hope they will someday read Toson Shimazaki’s Before the Dawn and feel something from it.
Closing
RubyKaigi this year was again a few days where changes in technology, changes in people, and time with family overlapped.
I listened to Matz’s talk and tried Spinel, and I felt a new direction in Ruby optimization through Sasada-san’s talk. I saw company members attend RubyKaigi and take on LT talks. Connections with former teammates are still continuing, thin but long.
In Hakodate, seeing my child cry because of the flight delay taught me how much they had been looking forward to the trip. I saw the night view from Mount Hakodate, saw the cherry blossoms at Goryokaku, and thought about history, daily life, and the flow of time.
Maybe I do not need to force all of this into one neat conclusion. RubyKaigi has become a place where I think not only about technology, but also about how I live, who I spend time with, and what I pass on to the next generation.
The dandelions were big