Well... I don't really know where to start... The saiki Kusuo no psi-nan ONA is clearly a very early anime adaptation of the manga, with the story, chatacters and the scenario being directly ripped out from the first volume. I cannot say that this is bad though, with comedic moments being really well executed and the characters captured almost perfectly. However, this is nowhere as good as the official (proper, full, 2016) anime adaptation, which is why i cannot give this a higher rating. The art style is crude and very primitive, as well as the voice acting being very quite poor. If you want to watch ananime adaptation of the manga, watch the 2016 anime Saiki Kusuo No psi-nan, you wont regret it. (The events in this ona even occur there, so you wont miss anything)