Meroi

Meroi (メロい) is a Japanese adjective describing someone or something so irresistibly attractive that it makes you completely smitten, weak in the knees. It is most commonly used when a fan’s oshi (favorite idol, performer, character, etc.) does something that overwhelms them with lovestruck feelings. It is not limited to romantic contexts, though; stunning visuals or performances can be meroi too.

In 2024, meroi was selected for Sanseido’s “New Words of the Year,” signaling its growing recognition beyond otaku circles and youth slang.

The word is formed by attaching the adjective suffix -i to the Japanese mimetic word meromero (メロメロ), which describes being head-over-heels infatuated with someone. It follows the same word-formation pattern as emoi (emotional → エモい) and chirui (chill → チルい), where an existing word is turned into a casual adjective by adding -i.

An alternative theory suggests the English word “mellow” as the source. However, since the word’s actual usage aligns more closely with the swooning nuance of meromero, that is considered the prevailing view.

The exact first use has not been pinpointed, but by the late 2010s the word was already appearing on platforms like X (formerly Twitter) among idol fan communities.

How meroi differs from emoi

Emoi expresses sentimental, nostalgic emotions, the kind that tug at your heartstrings. Meroi, on the other hand, leans toward romantic excitement: the flutter of butterflies, the feeling of being swept off your feet. Watching old footage of your oshi might be emoi; being floored by their live performance right now is meroi. The emotional direction is slightly different.

Derived expressions

The shortened forms mero (めろ/メロ) are also used as exclamations on social media. Phrases like “oshi ga mero” (my oshi is mero) or “mō mero” (I’m so mero) function as quick, punchy reactions.

There are also noun-like derivatives such as mero-otoko (メロ男, “mero guy”) and mero-onna (メロ女, “mero girl”), referring to someone so attractive they make everyone around them swoon. A typical usage would be “that person is totally a mero-otoko,” describing the one who triggers meroi feelings rather than the one experiencing them. These expressions have taken hold primarily in fan communities on social media.