[4] Kostiukovich/Ialin made their international debut in late September 2017 at the Junior Grand Prix (JGP) competition in Zagreb, Croatia, where they won the gold medal.

[6] In January 2018 Kostiukovich/Ialin won the bronze medal at the 2018 Russian Junior Championships after placing eleventh in the short program and second in the free skate.

They were part of a Russian sweep of the pairs' podium, along with their training partners Anastasia Mishina / Aleksandr Galliamov (bronze) and Daria Pavliuchenko / Denis Khodykin (gold).

They were ranked first in both the short program and the free skate and won the gold medal by a margin of more than 14 points over the silver medalist, their teammates Anastasia Poluianova / Dmitry Sopot.

They were ranked first in the short program and second in the free skate, and were beaten by the gold medalists, their teammates and training partners Kseniia Akhanteva / Valerii Kolesov by a margin of about 4 points.

They won the short program at Junior Worlds, narrowly ahead of both of the other Russian teams, and were awarded a gold small medal for the result.

In April, Kostiukovich and Briukhanov parted ways with their longtime coaches Ludmila Velikova, Nikolai Velikov, and Vasili Velkikov to move to the camp of Vladislav Zhovnirski and Arina Ushakova in Moscow.

[12] (with Ialin) JGP: Junior Grand Prix Small medals for short and free programs awarded only at ISU Championships.