Mayuchaya won her first and only major international title in the 1946 season. She was the foremost javelin athlete that season through her new best of set that July. At the 1946 European Athletics Championships she threw a championship record of to claim the gold medal ahead of fellow Soviet Lyudmila Anokina. She was part of a Soviet medal sweep of the women's throws, alongside Tatyana Sevryokova and Nina Dumbadze. At the Soviet Championships she won both the javelin and grenade throw events.