Category
- Band stories
Written by
Son Yang (Director)
Date
Mar 12, 2026
From the world's top universities such as Harvard, UC Berkeley, Carnegie Mellon, and Columbia, to Silicon Valley VC Mayfield with over 50 years of history, Sequoia Capital (Scout Fund), a16z (Scout Fund), and even the founders of Robinhood and Ramp—there is an AI that the world's leading universities and investors are scrambling to choose. It is the AI scoring platform, Pensive.
At first sight ❤️
It was in August 2023 that I was first introduced to Mr. Yang Yun-seok, CEO of Pensive. Mr. Jeong Sang-yong, CEO of Relate, introduced me to him as a promising entrepreneur among his juniors at Minjok High School. When I first contacted him, he was in the middle of pivoting and hypothesis testing, so he asked to meet in one or two months, and I waited.
Exactly one month later, CEO Yang Yun-seok contacted us saying he would like feedback on the product he was working on at the time, and we scheduled a meeting with Luke Lee (CEO).
On October 4th, we exchanged greetings over our first call and were able to hear an explanation of the hypothesis and the product (AI-generated Google Slides for Teachers). Luke Lee (CEO) offered the opinion that "it seems like a good product, but realistically, we need to quickly test how willing professors are to pay for it."
That day, CEO Yang Yun-seok visited the professors who had been using the service for free and asked about their willingness to pay, and pivoted the very next day. It was a very impressive speed and decisiveness, and with that first call and this short process, I felt that I wanted to invest immediately, regardless of what he did.
So, Pensive pivoted to a B2C-focused AI Tutor in November, and I learned more about it by meeting and talking with him in person during his business trip to the U.S. in January, when he had established some funding plans.
Yang Yoon-seok, a crazy person🔥
CEO Yang Yun-seok, born in 2000, is a founder who appears to be a model student who has followed an elite track, both in his background and presence. After attending Daewon International Middle School and Minjok High School, he graduated from the Department of Electrical Engineering and Computer Science at the University of California, Berkeley, on a full scholarship. He gained experience working as a Growth Engineer at Noom, a SWE & ML Researcher at Riiid, and a Tensorflow SWE Intern at Google.
In a way, he might be regarded as nothing more than a very diligent model student, but beneath that facade lay a highly rebellious and extraordinary journey. For instance, CEO Yang Yun-seok first visited Noom to intern when he was 14 years old, and the following is a memo I wrote at the time after hearing that story.
After entering university, CEO Yang Yun-seok was accepted for the special military service exemption program at every company he applied to, including Dunamu and Riiid, but he chose Riiid, which offered the lowest compensation. This was because, having moved from Jeju Island to Seoul at the age of 10 and attending Minjok High School and Berkeley, he deeply contemplated the disparities and issues regarding the educational environment, and ultimately became fascinated by the idea of solving problems in learning and education through technology.
He did not originally have any experience in engineering or AI. When Riiid offered to place him in any position he desired, CEO Yang Yun-seok started as an iOS engineer, believing that proficiency in app development would be beneficial for the startup, even though he was unfamiliar with iOS. During this process, he took on the entire project from start to finish and launched a product within just three months. However, working as a SWE, he felt that AI was still a "black box" and sought to pursue AI research. Since first-year undergraduates were not accepted as AI researchers, he participated in the largest Kaggle competition at the time to create a model that outperformed Riiid's internal benchmark, thereby persuading the internal AI research team. As a result, he became Riiid's youngest AI researcher. Subsequently, as an AI researcher at Riiid, he published papers as a first author in various top-tier AI conferences, and by the time his alternative military service ended, he had written more papers than master's degree graduates.
CEO Yang Yun-seok's Riiid Special Military Service Program: 
Yoonseok YangA Military Service Unlike Any Other
Yoonseok YangA Military Service Unlike Any OtherAs such, CEO Yang Yun-seok possessed exceptional challenging spirit, execution ability, and persistence, but impressively, he was also someone who sought feedback from those around him to gain metacognition about himself throughout his entire journey, starting from his high school days.
After learning about these processes, CEO Yang Yun-seok no longer appeared to me as a mere model student. I became convinced that he is an S-class "crazy" founder in terms of all the capabilities and qualities a founder in their early twenties should possess, such as a huge desire to build a generational company, a massive market, an obsession with growth, receptiveness to feedback, and the ability to execute without hesitation.
First investment ✨
And as always, it wasn't easy to secure an investment room from such a crazy founder. There was fierce competition, and at the time, BASS Ventures didn't have much experience investing in the U.S., so it wasn't easy to convince them of the value we could offer. During that process, the founders of Base (MarkVision, Offright, SlashPage, etc.🙏) generously helped with our reference checks, and as a result, fortunately enough, Base became Pensive's first investor. We also formed a connection with Jack, the co-founder of Hims & Hers whom we connected him with, who invested alongside us.
And this article captures the journey to get here from CEO Yang Yun-seok's perspective. 2023 was truly an extraordinary year.
As expected, the hard work begins 🥹
And as always, the hardships began from this point.
The AI tutor that the Pensive team was developing for universities and college students faced many structural challenges. For the product sold to professors and teaching assistants, it was difficult even to understand the purchasing decision processes that varied so widely from school to school; furthermore, the sales cycle was very long, and needs were highly fragmented. For the product used by students, the conversion hurdles were high, usage frequency dropped outside of exam periods, and, most importantly, many users employed it to achieve efficiency bordering on cheating rather than for effective learning.
In fact, the process of creating two products—one for professors and one for students—with only two people made resource allocation difficult, and we were repeatedly passed on by YC and others for reasons ranging from whether it was B2S or B2C to the fact that the edtech sector takes too long.
During this process, Jack, a co-founder and initial CTO, left the team. A brilliant 21-year-old engineer, he had a different perspective from CEO Yang Yoon-seok regarding the long journey of building a generational company. Fortunately, however, Minjun—a "super engineer" who had been working closely with CEO Yang at Riiid—moved to the U.S. alone to join us full-time. Together, we lived in a dormitory and led the product and technology development.
(For the first year and a half, the Pensive Team's office was CEO Yang Yun-seok's living room.)
With the advent of the great AI era, I felt anxious watching products like Cursor and Lovable gain traction at an unprecedented speed. Honestly, I wondered if I might grow much faster if I pursued something other than edtech, and I was also worried about the runway. I remember what CEO Yang Yoon-seok told me during those difficult times.
I believe the EdTech market has been bound to be small until now because it focused on assisting with the logistics necessary for learning, rather than providing the learning itself. Now that AI is opening up opportunities to deliver learning itself, I believe a historic company worth over $100 billion will undoubtedly emerge in the education sector. And we are dedicating ourselves to this work precisely because we are capable of making that happen.
Gaps Found: AI Grading 💯
About a year after the initial investment, CEO Yang Yun-seok mentioned that he felt he had found a clue. It was not AI Tutoring, but AI Grading. It was about automating the process of grading the answer sheets of all university students. This product was a model that accurately solved the repetitive and inefficient problems of universities and allowed for the rapid acquisition of revenue and data from schools. Structurally, if schools adopted it, students would naturally use it as well, unique data that did not exist elsewhere would accumulate, and once fully implemented, a picture was drawn of expansion into more areas.
Based on this opportunity, we quickly developed and launched a product, collected data, and published a paper , and the response came quickly.
AI Grader was introduced in over 100 classes at more than 30 top-tier U.S. universities, including Harvard, UC Berkeley, Carnegie Mellon, and Columbia, and 500,000 questions and answer sheets were graded in a short period of time. An education company with a multi-trillion dollar valuation even made an acquisition offer. One professor who adopted Pensive even shed tears of emotion after testing it.
Seed round swept by top US VCs 🚀
Many people say that edtech is a graveyard for startups. This was especially true in the realm of higher education, as opposed to K-12 education or workplace/casual education. Selling to universities was considered a business that made almost no sense. However, when we demonstrated our mission, speed, tenacity, and results, the reaction changed.
From existing shareholders to new ones, Pensive quickly secured three lead term seats. Frankly, it was the first time I had witnessed "true US VCs" vying to lead a Korean founder at this stage. As a result, this round was led by Mayfield, a Silicon Valley venture capital firm with a 50-year history that made early investments in Lyft and Hashicorp, followed by participation from Sequoia and a16z's scout fund. Furthermore, the founder of Robinhood, which built a trillion-dollar company, made an angel investment through Base's introduction, and the co-founder of Ramp, which built a trillion-dollar company, immediately resonated with the problem and the team and joined the team. Also encouraging is that the founders of Gradescope, currently the most widely used grading SaaS service by US universities, participated as individual investors after their exit.
Witnessing CEO Yang Yun-seok’s remarkable growth not only in terms of metrics but also as a founder, Base naturally decided to make a follow-up investment. During our internal discussions following the recent IR and investment deliberation, our assessment of CEO Yang Yun-seok was as follows:
Among Base Portfolios, execution ability, the magnitude of the vision, and the founder's growth rate are in the top 1%
Completely evolved from a college student into an entrepreneur
It feels like the vision and growth path are clearer than before, and I can feel that I have grown tremendously.
I consider him a founder who is persistently, quickly, and surely executing the starting point toward a grand vision; he does not lose sight of the long term while possessing excellent execution skills in the real world.
It seems that the founder possesses top-tier capabilities in various aspects, such as the specificity of the plan, the scale of the dream, and the speed of execution.
Pensive is now an AI solution used by over 1,000 professors in the United States and has graded more than 3 million answer sheets. However, this is just the beginning. The dream of Pensive and CEO Yang Yoon-seok is not merely the innovation of university education. It is to create an AI-native learning institution and solve the problem of 'learning,' which is the most important issue for humanity in the AGI era, through education optimized for individuals.
"We started Pensive because we believe that, for the first time, personalized learning is possible at scale. But scale alone isn't enough. The rise of generative AI has made it easier than ever for students to outsource their thinking entirely. The risk isn't just that students get wrong answers. It's that they stop wrestling with questions at all."
We live in a world where CEO Yang Yun-seok has been able to realize his dreams, and we believe that tremendous opportunities exist within this. Furthermore, we are confident that the Pensive team will undoubtedly be able to build the first and largest generational edtech company.
Finally, if you would like to join our amazing team, please check out the recruitment page below and the recently uploaded EO video!
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