Episminias Nikolaos Kostorizos served in 21 Mira (squadron) during the Italian invasion of Greece.

21 Mira started the conflict equipped with PZL P.24 but re-equipped with ex-RAF Gladiators in late 1940.

On 9 February 1941 18 S.79s from the 104^o Gruppo were out to bomb in the Kelcyre-Tepelene area. These bombers were escorted by twelve Fiat G.50bis fighters from the 24^o Gruppo led by Maggiore Eugenio Leotta, and twelve Fiat CR.42s from the 160^o Gruppo, led by Tenente Edoardo Crainz. Four Greek Gladiators of 21 Mira (Sminagos Ioanis Kellas (CO of 21 Mira), Anthiposminagos Anastasios Bardivilias, Episminias Ilias Dimitrakopoulos and Episminias Kostorizos) and eight PZLs from 22 and 23 Mire intercepted the formation.
The Greek fighters didn’t manage to penetrate the fighter screen and a series of hectic dogfights started with the Italian escort. Overclaiming was heavy on both sides and the Greek pilots claimed eight enemy fighters, Kellas claimed two while Bardivilias, Dimitrakopoulos and Kostorizos claimed one enemy aircraft each. Episminas Epaminondas Dagoulas of 22 Mira claimed one fighter while Yposminagos Marinos Mitralexes from the same unit claimed one fighter over Berat; Mitralexes also claimed one additional fighter and a probable during the combat. The Greek Army confirmed the eight victories and this was also confirmed by a Mr. Roussos, a journalist of the newspaper ELEYTHERON BHMA, who was on the ground with the troops as a war correspondent. His report is a first hand account and also gives the enthusiasm of the Greek soldiers while the Italian planes fell to the ground.
The Gladiators flown by Kellas and Dimitrakopoulos were both hard hit during the combat but it was possible to repair these fighters. Yposminagos Kotronis was shot down, but he managed to force-land his PZL, totally destroying it in the process. He escaped, however, only lightly wounded. A second PZL was shot up by three fighters and Episminias (Sergeant) John Michopoulos of 22 Mira was wounded in the thigh, but he managed to get back to Salonika/Sedes and land. Other aircraft returned damaged.
The G.50bis pilots in return claimed one Gladiator and three PZLs shot down, while the pilots from the 160^o Gruppo submitted claims for three Gladiators (one each by Tenente Crainz, Sergente Maggiore Luciano Tarantini and Sergente Maggiore Aurelio Munich) and two PZLs (Sottotenente Raoul Francinetti and Sergente Antonio Crabbia).
It seems that no Italian fighters were lost on this occasion.

Kostorizos ended the war with one biplane victory.

Claims:

Kill no.	Date	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1941
1	09/02/41	1	Enemy fighter (a)	Destroyed	Gladiator		Kelcyre-Tepelene area	21 Mira

Biplane victories: 1 destroyed.
TOTAL: 1 destroyed.
(a) Claimed in combat with fighters from 24^o and 160^o Gruppi. The 21, 22, 22 Mire claimed eight enemy fighters for the loss of one PZL while several more were damaged. The Italian fighters claimed five PZLs and four Gladiators without loss.

Sources:
Air war for Yugoslavia, Greece and Crete - Christopher Shores, Brian Cull and Nicola Malizia, 1987 Grub Street, London, ISBN 0-948817-07-0
Personal letter to Lars Larsson from Greek Airforce historical archive.
Additional information kindly provided by Dimitrios Vassilopoulos.