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"Because abacus is so much fun, I've been practicing it every day."

Rinne Tsujikubo, 2nd year student School of Education

At Toyama Hill on Toyama Campus, with her beloved abacus and the official certificate for her Guinness World Record for Flash Mental Arithmetic (2023)

 Rinne Tsujikubo won the senior division of the Soroban Grand Prix Japan 2024, where over 300 people selected from across the country competed in a fierce battle. She has had a remarkable career since before entering university, winning the elementary school student division of the All Japan Abacus Championship when she was in third grade, and breaking the Guinness World Record for flash mental arithmetic (※1) when she was in her third year of high school. She continues to participate in various competitions enthusiasitcally. We asked Tsujikubo about what motivated her to start abacus, the secret to her continued practice, her practice routines, and her future goals.

(※1) Mental calculation of numbers that flash on a monitor screen, etc.

--What made you start learning abacus?

It all started when I was in kindergarten and my mother took me to an abacus class, which I still attend today. It was there that I first said I wanted to compete. I think that's how much fun abacus class was and how much it suited me. I also took other lessons such as swimming and piano, but in sixth grade I quit all of them and started to focus on abacus. Then my skills improved, and I started to enjoy it even more.

Also, the presence of friends who attended the same class as me was a big factor. I have a friend who is the same age as me and enrolled at Keio University, who started attending the same day as me, and we still continue to study abacus together, encouraging each other and working hard in class. Also, we often travel around the country for competitions, and on those occasions, I make friends of the same age. I think it's thanks to the presence of such good rivals and friends that I've been able to continue enjoying abacus.

Left: A photo taken when she was in the third grade of elementary school and won my first national championship at the All Japan Abacus Championship.
Right: When she was in the second year of junior high school, she part of a team won the All-Osaka Open Abacus Championship. Tsujikubo is in the center of the back row.

--What kind of practice do you usually do?

I usually work on practice sheets for the competition I'm aiming for. The basics of abacus are the four arithmetic operations and guess calculations (※2). In addition to those, there are slip calculations (※3), mental multiplication, mental division, guess calculations, etc. In competitions, these are called individual all-around competitions, and in addition to the basic form, each competition has its own divisions such as read-aloud calculations, flash mental calculations, and English read-aloud calculations. However, even though they are all called individual all-around competitions, the judging criteria differ depending on the competition, such as whether accuracy or speed is emphasized, so I pay attention to these things when practicing.

(※2) A method of calculating numbers arranged vertically from top to bottom.
(※3) A method of calculation by flipping through a booklet containing multiple pages of numbers.

Since my abacus skills deteriorate if I don't practice even for a day, I have been practicing every day since I started. I practice not only at home but also in a classroom every day, so I practice for about three hours a day on weekdays and about five hours on weekends. I often practice all day during long holidays and before competitions. As all I need is a practice sheet and a pencil to do the minimum amount of practice, I used to take it with me on school trips in junior high and high school to practice.

The practice sheet she usually works on. The problems are created by her teacher at the class she attends, and by continuing to practice how many points she can get in 5 minutes, she is practicing to increase the range of digits in her mental arithmetic. The difficulty level increases every 10 problems (click to enlarge)

- Having participated in various competitions, is there anything that made an impression on you?

There was a competition called the "Tokyo Open Abacus Contest" in May 2025, and the days before the competition were tough. In fact, I had won the individual all-around competition four times in a row since the competition was established in 2021, so I felt more pressure than I expected... But participating in the competition itself is fun, and even if I fail, I just have to try harder in the next competition. I overcame the pressure and ended up winning the championship and achieving my fifth consecutive victory.

Video introducing the "Tokyo Open Abacus Contest" held in 2024 (Video provided by the TOKTO OPEN SOROBAN CONTEST Executive Committee)

--How did you feel when you won the senior division of the Soroban Grand Prix Japan 2024?

Actually, I had won the junior division of this tournament five times in a row. In that sense, I felt the same pressure as I did at the Tokyo Open Abacus Contest, but I was worried that the way of competing would change from the junior division to the senior division for people 18 and over. The former emphasizes speed over accuracy, while the latter requires more accuracy in calculations while maintaining a stable speed, and you can't make even one mistake to win. So, when I won, I felt relieved, but I was also surprised and overjoyed because I never expected to win.

The award ceremony for the "Abacus Grand Prix Japan 2024." Tsujikubo is in the center.

--Please tell us what has motivated you to continue using abacus.

The word that sums it up is "fun". By participating in various competitions, I was able to make new connections with other athletes of all ages. Of course, I feel joy when I achieve good results in competitions and regret when I don't, but more than that, the friends I've made through abacus are precious and irreplaceable to me.

I also started learning abacus because I said I wanted to do it myself, but at first, I was too nervous to ask the teacher when I didn't understand something. But thanks to my mother who supported me in practicing after coming home, I was able to continue, and I have won many awards so far. I'm always happy when I win a prize, so I want to win again next time. I currently take part in about 10 competitions a year, and because there are so many competitions, I have goals to aim for, and I don't have time to be depressed even if I lose.

A photo of the first victory in the "Soroban Christmas Cup" at the end of 2024

--Please tell us about your future goals and plans after graduation.

My future goal is to win many competitions! First of all, I want to win the All Japan Abacus Championship in August 2025. This is a prestigious competition that has been held since 1954, and if I win, I will get the title of Japan's best abacus player, so I would like to win it. In addition, this year there is also the "Abacus Master Title Decision Tournament" held every two years, and I am aiming to win there as well. The previous master, Takuya Yatani (graduated from School of Culture, Media and Society in 2023) and the master before that, Haruto Horiuchi (graduated from School of Education in 2025), are both seniors from Waseda University, so I hope I can join this trend. Also, my Guinness record for flash mental arithmetic was broken, so I would like to get it again! Even if you have the ability to break a Guinness record, there are few opportunities to officially prove it and receive certification, so it is difficult to beat a Guinness record. 2025 is also the year I will be turning 20, so I would like to make it a year of success.

After graduating, I would like to find a job where I can use my abacus skills. Looking at my seniors who used abacus, I see them working as bank clerks or opening abacus classes and becoming instructors, so I am interested in those paths. I think the concentration and perseverance I developed through abacus are useful in any profession, so I would like to make use of them in the future.

904th

Interview, text and photography: Waseda Weekly Reporter (SJC student staff)
Honoka Yasunobe, 3rd year School of Culture, Media and Society

【Profile】

A photo from when I went to an ENHYPEN concert.

Born in Saitama Prefecture. Graduated from Waseda Jitsugyo High School. Whenever she sees a number, she reflexively converts it into an abacus, so she will do some kind of calculation at random times in her daily life, such as doubling a certain number forever or making 10 with a car license plate number. She likes listening to music, and genres range from J-POP to K-POP. By the way, the first live performance she went to was a sumika concert, and her favorite songs are "Sakamichi, Shiro wo Tsugete" and "rem.". As for K-POP, she often listens to SEVENTEEN's "Our dawn is hotter than day" and "Domino." Her recommended Wasemeshi are "Abura Soba Specialty Store Menji," "Donpishari," and "Takada Bokusha."