It's an old manga. If I'm not wrong it's a one shoot. There is a guy "A" that got prank by his friend with love letter, and believe it. And there is another guy "B" who know it. Then I don't really remember. If I'm not wrong A think the love letter is true and come to the place in love letter. B then tell A about the truth. I'm not sure if it's the correct plot, but it's all I can remember. I remember liking the art, but forget the title. Anyone know??