Marulu is a kind and notably friendly individual who expresses outright interest in Earth's culture. His feelings also seem to be somewhat easily hurt based off his reaction when he was berated for asking what a Curse User was and whenever Yuka and Tsurugi left him at the start of their first mission, where he sat on the ground and began to cry. However, he does have a more serious side, being incredibly faithful to his mission of seeing if it is possible to co-exist with the humans on Earth.