if kudou really killed the actual reiko, which is the person he loves, and he feels guilty about it and can’t moving on from her...... maybe that’s why he gave reiko’s clone a goldfish?? so that she’ll always stays in kowloon as the actual reiko’s substitute??? and the fact that kudou doesn’t want to change the old ways of him living in kowloon is probably because he still loves reiko so that’s why he always stuck in nostalgia??