Early years Retamar when he was sixth grade was selected by
Batangas province to represent
Calabarzon in a regional competition. Originally a libero, this marked Retamar's transition to a setter. He also played for the University of Perpetual Help–Biñan high school team. He was being scouted by the
De La Salle Green Spikers before the
NU Bulldogs made a last minute offer to convince him to commit to the collegiate team. Later on, the tournament was cancelled due to the COVID-19 pandemic.
Club Retamar was signed by the
Sta. Elena Ball Hammers in 2018. He won best Setter award in the
2019 Spikers' Turf Open Conference. His team bagged the bronze medal on that season. In 2022, he became the captain of the team. After graduating from NU, Retamar joined the
Cignal HD Spikers in May 2024. He helped Cignal win four
Spikers' Turf championships and was named best setter three times. He stayed until the club's disbandment in January 2026. The following month, Retamar joined Cambodian club Visakha for the Sar Kheng Cup.
National team In December 2019, Retamar made his debut for the
Philippines national team helping them win silver medal in the
30th SEA Games which was hosted at home. Retamar returned to the national team at the
2024 AVC Men's Challenge Cup. He also played at the
2025 FIVB Men's Volleyball World Championship which was hosted by the Philippines as well as helped the national team win a bronze medal at the
2025 SEA Games in Thailand. ==Clubs==