Maria Viren is a Russian woman from a poor town who initially made a living by prostituting herself to tourists. At the age of fifteen she was adopted by a wealthy Taiwanese man, but when he died it was discovered that he had left behind substantial debts, prompting her to join the Bugs Project, the second manned expedition to Mars, in order to pay them off. She is twenty-four years old, stands 170 centimeters tall, and weighs 56 kilograms. Her hobby is drawing, and her favorite food is miso soup.

In terms of personality, Maria appears easygoing and unbothered by the prospect of encountering cockroaches. Aboard the spaceship Bugs 2, she laughs at Komachi Shokichi for being afraid of them, remarking that she was raised with cockroaches without knowing it, so she has no fear of them. When the expedition lands on Mars, she expresses surprise that the planet is not cold and that moss covers the ground. Her primary motivation is financial: to settle the debts left by her adoptive father, and she joins the mission without any apparent ideological attachment to its goals.

Maria undergoes the Bug Procedure, with her DNA based on the Rainbow Stag Beetle (Phalacrognathus muelleri). In her transformed state, her hands develop a beetle-like carapace that she can use for defense. Despite the natural strength of the shell, it proves insufficient against the Terraformars. Shortly after arriving on Mars and transforming, she is killed by a powerful kick from one of the mutated humanoid cockroaches that cuts her body in half. Her role in the story is that of a supporting crew member on the BUGS2 expedition, and her death underscores the extreme danger posed by the Terraformars and the high casualty rate of the mission. She has no significant character development beyond her initial introduction and demise, and her key relationship is a brief, lighthearted exchange with Komachi Shokichi before the landing.