Takehiko Henmi  

Oniisama, 辺見 武彦

The "dear brother" mentioned in the title refers to Takehiko, who is a reassuring figure that Nanako confides in through letters. Although they share an elective relationship, Takehiko has a greater impact on Nanako's life than she may realize. He is currently studying at university and aspires to pursue an academic career abroad, particularly in Germany. Despite being quiet and serious, Takehiko deeply cares for Nanako.