Ranma ½ - Season 1 Episode 158

Ryoga encounters Checkers (Shirokuro) a black and white dog. The dog saves P-chan when they went over a waterfall, so Ryoga starts to take care of the dog and feed it. The dog takes a love letter Ryoga had written out of his backpack and delievers it to Akane. Akane doesn't know who the letter is from because Ryoga didn't sign it, but gives Checkers a letter to give to return. The letter said that she had someone that she loved, and was sorry she couldn't return the writers feelings. Ryoga is horrified when he reads this, but then Ranma asks him if he had signed the letter Akane read. Upon realizing that he hadn't, Ryoga believes that the 'somebody' Akane is talking about is actually him.