Hibiki Nishiwaki

Hibiki Nishiwaki is a Japanese competitive programmer and third-year Computer Science undergraduate at the National University of Singapore. He won a gold medal representing Japan at IOI 2023 (rank 25 of 350, 344.50/600). He competes under the Codeforces handle 'penguinman', holding International Grandmaster with a peak rating of 2716, and was part of the NUS team that placed 25th at the ICPC 2025 World Finals. He appears as a Guest in Japan's IOI 2025 delegation. His LinkedIn lists him as a Teaching Assistant at NUS.

Notes8

• Competitive-programming identity 'penguinman' on Codeforces is Hibiki Nishiwaki: CPHOF's profile links the Codeforces handle penguinman, and clist.by groups the penguinman account with cphof/ioi:8077 under one coder page.Sep 4, 2025
• IOI 2023 gold medalist representing Japan: rank 25 of 350, score 344.50/600, on the 2023 team (IOI profile lists task scores closing 83, longesttrip 60, soccer 77.5, beechnetree 5, overtaking 65, robot 54).Sep 4, 2023
• Quant employment verification: UNRESOLVED. The only employment lead is an unverified index entry claiming a Hudson River Trading Software Engineer Intern role for May-Jul 2026; no primary or corroborating source (LinkedIn, HRT, press, code) confirms any HRT role, internship, or offer. Hudson River Trading is a proprietary/algorithmic trading firm, so IF the role were real it would qualify as quantitative trading, but the employment claim itself is unconfirmed and must not be treated as fact; it also cannot be distinguished from an incoming offer versus completed work.
• Member of the National University of Singapore team ('Jägermeister') that placed 25th at the ICPC 2025 World Finals (Baku, Azerbaijan, 04 Sep 2025), alongside Roman Yanushevskyi and Yuto Watanabe.Sep 4, 2025
• LinkedIn headline 'IOI 2023 Gold | Y3 CS @ NUS' with current role Teaching Assistant at National University of Singapore and location Singapore; third-year Computer Science undergraduate.
• Codeforces account penguinman is an International Grandmaster, current rating 2672, max 2716, registered ~7 years ago, country Japan.
• Listed in the IOI 2025 Japan delegation as a Guest, indicating continued involvement with the Japanese IOI program after competing in 2023.2025
• Devfolio account @hbknishi hosts project 'PTPh' ('Medical Helper'), built at the Push to Prod Hackathon with Genspark & Claude under the team name one_day_to_final_exam.
• Public LinkedIn post activity attributable to the account includes a post about Deedy (@deedydas); LinkedIn itself is not machine-readable here (blocked), so post content could not be verified first-hand.