oira

In Japanese, oira おいら is a first person pronoun used mostly by men, and, in some cases, a second person pronoun, too, as the plural of onore 己.

It's also spelled oira オイラ, or oira 己等.

Manga: Boku no Hero Academia, 僕のヒーローアカデミア (Chapter 46, 怪奇！グラントリノ現る)

• First Person Pronoun
• Second Person Pronoun
• References

First Person Pronoun

The word oira means the same thing as ore 俺, it originates in a change of pronunciation on the word orera 俺ら.^{(デジタル大辞泉)}

This ~ra ～ら is a pluralizing suffix, so the word orera means "we," or "us." Similarly, oira originally meant "we" or "us" in the plural, but modern usage is singular: "I," "me."

Confusingly, oi おい is also a first person pronoun by itself.

Manga: Boku no Hero Academia, 僕のヒーローアカデミア (Chapter 46, 怪奇！グラントリノ現る)

• oira wa
  Mt. (maunto) Redhi!!
  オイラはＭｔ．（マウント）レディ！！
  I'm Mt. Lady!! (No! Wrong!)
  For me, [it's] Mt. Lady!! (correct.)
  • Context: Mineta picked Mt. Lady for a thing.
    What thing it was doesn't matter.
    What matters is: the wa は particle here means "as for."
    For you, X. For me, Y.
    For you, the Flame Hero, Endeavor. For me, the giantess heroine, Mt. Lady.
    This is an example of contrastive wa は.

Second Person Pronoun

The word oira can also mean the plural of onore 己, that is, onore-ra 己等.^{(精選版 日本国語大辞典)}

Since onore can be used both to refer to oneself and to other people, oira can also be used as a second person pronoun.

References

• オイラ - デジタル大辞泉 via kotobank.jp, accessed 2021-03-28.
• オイラ - 精選版 日本国語大辞典 via kotobank.jp, accessed 2021-03-28.