100％ no Onnanoko ni Deaeru Kanousei ni Tsuite.

Yoshida Junichi is a man who was below average in every way, and he was fed up being ignored by women. One day, the owner of a mysterious antique bookstore gave him a book as a gift. It was a book of aphorisms full of corny pickup lines — boring! That shopkeeper must have sold out of good books! But if only he were confident enough to say such lines... A junior colleague of his encouraged him to talk to a beautiful woman they saw at a bar, but he was rebuffed. In a moment of despondency, a line from the book of aphorisms came to his lips: "I love you more than everything, more than the whole world."

Wait, what's going on? Something is wrong with this gorgeous woman... she is falling in love with me...! What is this book?

(Source: Mosh!, translated)