It is a high quality and popular vector drawing app (4+ stars on app store) and the code is clean and simple to understand. I am not sure you will learn anything by just reading through it if you're not building a similar kind of app though.
>A CutJS app consists of a tree of nodes, each node is pinned (transformed) against its parent and have zero, one or more image cutouts. Image cutouts comes from either image textures or Canvas drawing.
How much can you trust each bit of information you gained though? For example, it might be very possible that Light could be intentionally waking up at the middle of the night to do his killings. In which case you would've ruled out japan, which then ruins your subsequent analysis which is all somewhat based on him being in japan. Verifying every bit of information gained or even assigning a probability to how much you can trust it seems to be a hard problem.