Mara

The demon that tempted Buddha and tried to distract him while he was on the way to achieve enlightenment. Because Buddha never reacted to his seductions he tried to make Buddha laugh until he eventually succeeded. In the series he is depicted as a male humanlike being whose lower body is that of a snake. He also seems to be very tsundere. He is annoying Buddha by sending him masses of short mails on his phone or competing against him in various ways nowadays. Source: Wikipedia