Well, reading all the manga related to SK is the only way to understand something ahaha. I mean the plot of the sequel makes sense if you are WELL aware of ALL the events of the SK universe, otherwise you will surely get lost at some point.
Those who have not read SK 0 will not know what is happening in this first part of the chapter and will say that Takei is throwing stuff out randomly, when... it is not like that ahahha