be thick as thieves (bi ziku azu shivuzu)

Idiom Friendship

意味

to be very close friends

とても親しい友達である (totemo shitashii tomodachi de aru)

例文

"Those two have been thick as thieves since childhood."

"この二人は子供の頃からとても親しい友達です。" (Kono futari wa kodomo no koro kara totemo shitashii tomodachi desu.)