The final member of the 'Idol' team, Tycho is brash, impulsive, and utterly determined (at least in the beginning) to best Lal'C's long-standing kill record, seeing it as a chance to wipe the normally smug look off the face of the teacher's pet(another of Lal'C's nicknames among the members of the Fraternity). She has a low opinion of Topless in general (despite the fact that she's a Topless herself) due to an event in her childhood where -- in spite of her powers -- she was unable to cure the illness of a close friend, and is annoyed by Nono's constant attempts to prove herself worthy to become a Buster Machine pilot. Ironically, it is Nono who later helps her change her way of thinking for the better. While it isn't outwardly implied, the two become friends, though not on the same level as Nono and Lal'C.
SpoilerInitially Tycho pilots the Buster Machine No.66: Soixante-Six, but it is destroyed when (against her initial orders) she uses it to impulsively attack the Jupiter Express (a massive swarm of space monsters that roamed the space between Jupiter and Saturn). After a period of self-doubt, she is able to awaken Buster Machine Quatre-Vingt-Dix, and it remains her machine for the rest of the series.
In the epilogue, Tycho becomes an emissary of earth and travels to various systems with the corps. She wasn't present during the homecoming of Noriko and Kazumi.