Nee, Mokkai Neyo?

As children, Otaki Shinobu and Mori Shizuno swore to stay together forever, but they ended up becoming separated due to circumstances.
When they reunite as high school students after a long time apart, their differing memories of their past “promise” led to an argument.
Insomnia caused by the unfamiliar new life. A disappointing reunion. For the two of them, it was the worst possible start.

But—

By chance, they discover that they can finally rest peacefully if they fall sleep together.
From then on, they will sleep in the school infirmary, in Shinobu's room, at Shizuno's house, etc.
Confused by how much they've grown since those childhood days, they create their own “sleeping together rules”…

This is the story of two childhood friends who can't be honest with each other — frustrating, bittersweet, but warm.
A story of how they gradually rebuild their relationship by literally sleeping together.

(Source: Dengeki Bunko, translated)