Within Lucifer, missions were classified into seven grades—S, A, B, C, D, E, F—with F being the lowest and S being the highest. The Plan S against the Korean-Chinese Alliance was the highest grade for a mission in Lucifer.
The four generations of Lucifer's heads, including Si Yiyan, in its more than a hundred years of history, having been through the world wars, change of times, and various international politics, had but issued five Plan S, each of which concerned Lucifer's survival.
This showed the importance of Plan S to Lucifer.
Long ago, when Si Yiyan just took over as the head of Lucifer, Plan S was already issued. It was a secret operation customized for dealing with the Korean-Chinese Alliance that spanned over more than twenty years.
This included Si Yiyan wiping out the Korean-Chinese Alliance's powers in Italy and the "snake-catching" operation against them in Russia previously.
And over in China laid the core of the entire Plan S.
