Sem-Fray is a huge antibody that guards Memory Part. It takes shape of a large airplane.
Sem-Fray mainly moves left and right while shooting a spread of red lasers. After a few shots it dives to the bottom of the screen and releases various missiles which pursue the player's ship around. Upon returning it uses a green spreadshot.
After taking enough damage Sem-Fray leaves the screen, flying fast from one side of the screen to the other while shooting a barrage of red lasers or bullets. It does this three times before returning and resuming its pattern.