Chapter 33 in its entirety, as it is a Breather Episode after the intensely dramatic Volume 5, and centers on the personal lives of the characters.
Nanami's beloved embracing undeath to be with her at the end of chapter 19 is clearly intended to be this, but given the age gap and whole biting thing.
A minor one, but watching Mina playing jumprope with a group of children while they wait for their parents in Chapter Five is likely to induce at least one "Awwwwww!" from the reader.
In Chapter 36, Mina reuniting with her dead mother in the 'normal' world. It then becomes a Tear Jerker when it turns out to be a dream.
Oh Mina had more or less figured out this was some sort of hallucination well beforehand, but when her mom showed up she pretty much stopped caring.
In volume 12: So many. Mina's reunion with her maids, Nanami's reunion with Yuzuru, Akira's reunion with Mina especially...
In volume 13, during the Earth Clan lords' Heroic Sacrifice, Lord Connery dies after jumping in the way of a spear that would have killed Lord Ernest, despite knowing that none of them were walking away from that battle anyway, just because he doesn't want to see his friend die before he does.
When Yuzuru becomes a vampire so he can be with Nanami forever.