Even though Sony has taken the sidekick word, there are lots. The characters 愛(love), 相(together) have "ai" readings and are productive. The verb あう goes to an あい noun form that is productive for forming words like aizuchi. Plus various others.
aite
愛犬 aiken: beloved dog
相手 aite: companion, other party, opponent.
藍色 aiiro: indigo blue; 濃藍 koai: deep indigo.
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https://jisho.org/search/あい%3F
