Adachi and Shimamura, Vol. 4 (manga)

Adachi and Shimamura are now in their second year of high school. Luckily,they’re in
the same class this year, but Adachi doesn't seem toopleased with the fact that
Shimamura is having no trouble fitting right inwith their new classmates.
Acquaintances, friends, best friends—thoseare all well and good, but how do you take
that final step? Maybe having asleepover and sharing a bed together...?