It's a spin-off OVA from Hello World. No history-changing, time-travelling or anything like that. Just Naomi living in his world and doing his quiet thing. It's understated, civilised and only a little bit pointless.
RECORD 2027: feels like a compilation of film scenes. You'd need to take notes to work out which bits are new. That said, though, it's also quite nice. Naomi and Ruri are a likeable couple, in their socially awkward way. Ruri can't smile or be friendly. Naomi is walking wallpaper. They understand each other.
The other two Records are new material.
RECORD 2032: Naomi's now at university and determined to avoid fun. When girls try to come to his room, he stonewalls and tells them to leave. (This is because of Ruri.) He acquires a kitten, somehow, which in turn attracts a particularly stubborn girl who knows about cats and how not to look after them. This episode is morose and Naomi needs to study not being miserable.
The framing's also quite distant. It uses a few fixed camera angles, with its favourite one being a flat, somewhat detached view of Naomi's underwhelming student room.
RECORD 2036: a lighter episode, thanks to that bad-tempered Chinese girl. Naomi's now an adult with a job at a scientific institute, where he and Professor Senko try to avoid eating peppers/mushrooms and make it hard to clean the laboratories. Naomi has an accident that leaves him using a crutch, with the cause being the fact that he's pathetic.
Would I recommend this? Well... it's not bad. It's quiet and open-ended. I don't know how meaningful it would feel if you haven't seen Hello World, but it holds together well enough if you have. It's of a small amount of mild interest.