One Piece Chapter 12, page 12-13: Chapter 12: DOG

Boodle reveals the sad truth: 'No, he's not... He got sick and passed on.' Luffy looks surprised. Boodle continues, 'He went to the hospital three months ago.' A flashback shows the owner, an older man with a mustache and a dark knit cap, leaving for the hospital, waving back and saying, 'Awright, Chouchou... You're in charge of the shop while I'm in the hospital.' Chouchou barks, 'Ruff!' in response. Nami, deeply moved, says, 'The poor thing... You mean he's been waiting for his master this whole time?' Boodle replies, 'That's what everybody says, but that's not what I think.

Boodle explains his perspective as Chouchou quietly eats his food. 'Chouchou's a smart dog... I think he knows his master is dead.' Luffy listens silently from his cage. Nami asks, 'Then why does he still guard the store?' Boodle, looking at the shop, answers, 'It's his treasure. And I think that Chouchou still guards the store......because it's all that's left of his beloved master.