secret account; alt account; anonymous account
Internet slang for a secondary social media account used anonymously or for private posting, separate from one's main account.
I post my true feelings on my secret account.
She shares hobby photos on her alt account.
Standard mixed kanji-katakana spelling; アカ is from アカウント (account).
Ateji spelling using 垢 (あか) for 'account'; common in informal online writing but may be confusing for learners.
Compound of 裏 (うら, 'back, hidden') and アカ, a shortening of アカウント ('account'). The ateji 垢 is used for its reading あか.