This is the high school Sirius series for math II and math B, a textbook for cram schools. I'm a novice, so I don't know the details of the level, but I remember hearing that it's sufficient for mid-tier private universities. I've included a page I randomly opened and the corresponding explanation page, so please take a look and judge for yourself. The explanation booklet is thicker than the problem book, so I assume the explanations are thorough. Math II: main book 286 pages, explanation book 557 pages. *Please note that I cannot answer questions about level assessment, as mentioned above.