She studied at the Berlin University of the Arts under Martin Rupprecht and Vivienne Westwood. Since 2000, she has worked as a freelancer in theater, opera, and film, collaborating with directors such as Adriana Altaras, Jean-Yves Courregelongue, Hans Neuenfels, Daniel Schmid, Robert Wilson, and Marie-Eve Signeyrole. In 2009, she received the Hein Heckroth Sponsorship Award for Set Design.

For Robert Wilson, Yashi designed costumes for productions including Samuel Beckett’s Krapp’s Last Tape (Festival dei Due Mondi, Spoleto), Rumi: In the Blink of the Eye (Athens), Káťa Kabanová and 1914 (National Theatre Prague), Odyssey (Athens), La traviata (Linz, Perm), and The Tempest (Sofia). She received a nomination for the Golden Mask award in Moscow (2017) for her La traviata costumes, and in 2022, she was nominated for an Askeer Award for her costume design for Shakespeare’s The Tempest (directed by Robert Wilson) in Sofia.

Yashi has a long-standing collaborative relationship with Marie-Eve Signeyrole, working on productions such as Eugene Onegin, Gianni Schicchi, La notte di un nevrastenico, and Rigoletto (Opéra National de Montpellier); Owen Wingrave (Nancy); Carmen (Latvian National Opera); Macbeth and Negar (Deutsche Oper Berlin); Belshazzar and Roméo et Juliette (MusikTheater an der Wien); and Médée (Opéra-Comique, Paris).

She designed the costumes for Stefan Herheim’s production of Idomeneo for the 2024 reopening of the MusikTheater an der Wien. In 2015, Yashi was responsible for the costume designs for the European Games in Baku, earning an Emmy nomination in 2016.