Anessa Rossetti operates communications and radar as a Corporal bridge operator on the Free Pact Alliance warship *Cygnus*. She works with Mayuka Nasu under scientist Elvira Hill's supervision. Contrasting Mayuka's reserved nature, Anessa possesses an energetic, outgoing personality. She exhibits a playful, sometimes mischievous streak, particularly enjoying crew gossip. This is shown when she teases Elvira about Mayuka potentially having feelings for fellow crew member Aoba Watase.

Physically a teenage girl, Anessa has light purple hair—variously described as aubergine, light fuchsia, or purple—typically in pigtails, and yellow-amber eyes. She wears a standard pink military uniform indicating her rank aboard the *Cygnus*. Socially, Anessa displays romantic interest in male pilots, initially showing some attention to Dio Weinberg before shifting focus significantly to Fromm Vantarhei upon his arrival. She demonstrates immediate, overt attraction to Fromm, becoming visibly elated upon learning he would stay on the *Cygnus* and exhibiting clingy behavior towards him, contributing to ongoing ship tease.

During operations, Anessa provides support by actively monitoring Valiancer units in combat, feeding tactical data to command. Her observations prove critical, such as detecting anomalies in readings when Aoba Watase pilots the prototype Luxon unit, sparking crew investigations into his origins. At Narashino Base, her presence facilitates character moments, including observations of Mayuka's interactions with Aoba. She participates in the *Cygnus*'s deployment to the Battle of Alaska during the final conflict. Anessa maintains a consistent personality throughout the series, fulfilling a supporting narrative role through her operational duties and interpersonal dynamics.