On Page 3
The partial text: "魔法少女の魔力"
Can be translated as "magical girl abilities"
Making a guess based on context of what the cut of kanji was, my most likely guess is "源" which means source / origin
So if the text was "魔法少女の魔力の源" that would make it "magical girl abilities origin" or "origin of magical girl abilities"
Still learning Japanese though so I can't read Japanese completely on it's own yet