She's Adopted a High School Boy! Vol. 8 (Kodansha, 2021)

""If you're happy, I'm happy"" is the motto of the next-door neighbor who paid off Minoru Soramoto's family debt and took him in, all at no charge… Where will this exciting new life with the mysterious lady lead next?! After an April Fools' joke goes too far, Minoru finds himself transferring into the STEM track at school and striking up a friendship with Taiyo Matsuoka, a living caricature of a classic science nerd. Meanwhile, he discovers Shiori-san's last name, survives an incident with her underwear, and the two finally… The chemistry between them reaches a fever-pitch in this latest installment!