Batman has encountered some of the coolest and strangest heroes and villains during his time patrolling the streets of Gotham. However, when he went undercover with Martian Manhunter in Japan, he couldn't help but notice his fellow Justice Leaguer assumed the secret identity of a Sailor Moon heroine.
The Caped Crusader crossing over with Sailor Moon makes little sense on the surface; Batman is a masked hero who protects the citizens of Gotham while fighting his own rogue's gallery of villains, while Sailor Moon is one of the most popular and beloved manga and anime series of all time. Led by the titular Sailor Moon, the teenage Usagi Tsukino leads the Sailor Guardians from cosmic threats. But different as they may seem, the Sailor Moon heroes are confirmed to at least exist in the DC Universe, as confirmed in a Justice League comic.
In JLA #27 (1999) by Mark Millar, Mark Pajarillo, Walden Wong, Marlo Alquiza, Ken Lopez and Pat Garrahy, Batman, Superman, and Martian Manhunter are having lunch to discuss important matters of the Justice League. While Bruce Wayne and Clark Kent talk in the open, Martian Manhunter puts on a disguise. He shapeshifts into Hino Rei of the Nihon Kezai Shimbun, Japan's largest financial newspaper. Bruce immediately tells a disguised Martian Manhunter that his "name's a giveaway," and tells him he can still detect his Martian body language under the disguise. So, why might Bruce consider "Hino Rei (Rei Hino)" a giveaway? Because Rei Hino is the real identity of Sailor Mars from the Sailor Moon series.
Is Batman a secret Sailor Moon superfan? Does Martian Manhunter watch the anime or read the manga? That's never answered. Millar has previously denied the reference, telling CBR, "I was told it translated loosely as POET OF MARS, which is what J'onn's occupation was back on his homeworld. It had zero to do with Sailor Moon." But, I mean come on. You're telling me out of every secret disguise you chose the real-life name of Sailor Mars for the Martian character? That would be quite a coincidence. Maybe whoever fed him the translation snuck in the reference.
Regardless, the world of Sailor Moon seems to exist in the DC Universe. Martian Manhunter understandably relates to Sailor Mars and adopted her identity. Now... is this explicit confirmation Batman is a big anime fan?