Mujina is a member of Kaiju Eugenicists.
Mujina is a stoic woman who, by her own admission, has no goal in life she's working towards, a stance emphasized in her discussions with her fellow Kaiju Eugenicists where she says she'll do whatever they decide on.
The further irony of her character is that she did find something enjoyable as much as fighting as a Kaiju Eugenicist such as hanging out at a water park, going to a game center, drinking at soda joint, and watching movies with the others.
(Source: Gridman Wiki)