Shizuka Nanahoshi
Due to her desire to go back home and her unattached attitude to her current world, she tends to like being alone. She is serious when working and childish when it come to stuff from the old world. Shizuka spends all her time indoors and doesn't like meeting people as she doesn't want to grow attached to anyone in the current world. Spoiler Shizuka is a Japanese girl that was saved by Rudeus in his past life, but instead of reincarnating like Rudeus, she was teleported to the Asura Kingdom and was saved by Orsted. She has a disease that causes magic to accumulate in her body because she can't use it and it might kill her if it is left unattended. (Source: Mushoku Tensei Wikia)