Takashi helping to pull Saeko out of her Death Seeker funk.
Kohta giving Saya his MP5 and taking her pistol when she was complaining about feeling useless. This wouldn't be a huge deal most of the time, but for a gun otaku like Kohta it means a lot. The others who saw it treat them like they got caught making out.
A slightly morbid example from the third extra chapter has the undead Morita approaching the undead Misuzu (the BFF with Odango Hair). At least in death he finally got the girl....
Takashi saluting to his Ithaca shotgun after leaving it behind to get a more powerful gun is kind of heartwarming too.