Hanaya no Nikai de

This time, the focus is on the second eldest brother in the family from Mainichi Seiten — the bespectacled Akinobu who wakes up one morning in an unfamiliar bed with someone most familiar and unexpected. (Source: MangaUpdates)

This is the last in a series of stories:
1. Mainichi Seiten
2. Kodomo wa Tomaranai
3. Children's Time
4. Kodomo no Iibun
5. Isoganaide.
6. Hanaya no Nikai de

Although not specifically "sequels", this is the order that the stories were written/published in.