About the Arisa Manga Volume 5

(W/A) Natsumi Ando Twin sisters Arisa and Tsubasa, separated by their parent's divorce, are finally united after three years and Arisa asks Tsubasa to pretend to be her and spend a day in her school just for fun. At school everyone seems very nice to Tsubasa (who is pretending to be Arisa) and everything seemed normal - until she finds a strange note in her sister's shoe locker. After reading the letter, Arisa tries to kill herself. Tsubasa is determined to unravel the mystery behind the letter