noun
person who sits between host and guest of honor at a drinking party; companion at a drinking party
Refers to a person who sits between the host and the guest of honor at a formal drinking party, often to facilitate conversation and ensure the guest is attended to. The term carries an honorific nuance (御).
宴会では、おあいの方が主賓と主人の間にお座りになります。
At the banquet, the companion sits between the guest of honor and the host.
彼はおあいとして、会話が途切れないように気を配った。
As the companion, he made sure the conversation didn't lag.
The term is composed of the honorific prefix 御 (お) and 相 (あい), which here means 'between' or 'mutual', referring to the person who sits between two parties. The exact historical derivation is uncertain, but it is a specialized term from traditional Japanese drinking party etiquette.