共犯 means "accomplices" or "partners in crime", and Mrs.GREEN APPLE use it in a surprisingly warm way. The crime here is being human: getting hurt, hurting each other, and still holding on. The chorus line "傷を舐め合う僕らは 共犯 共犯" (we who lick each other's wounds are accomplices, accomplices) uses the idiom 傷を舐め合う, literally "licking each other's wounds". In Japanese it is a bit of a dig: it means comforting each other in a self-pitying way. The song admits that, then shrugs and calls everyone guilty together.
The best image for me is "社会というベッドに皆で眠る" (we all sleep together in a bed called society). Nobody gets real rest, as the next line says: "休まる事なんかは 無いのに 無いのに" (even though there's never any rest, never any rest). The verses are sharp too. "孤高と孤独は違うのよ" (being proudly aloof is not the same as being lonely) is a blunt little lecture, and 孤高 versus 孤独 is a great pair to learn: one is chosen solitude, the other is not.
The lyrics also mix in English loanwords written in katakana, like デスティニー (destiny), マインド (mind), アジャスト (adjust) and ベット (bet). "未来に全部ベット出来る理想が湧かない" (I can't come up with an ideal worth betting my whole future on) is a gambling metaphor, and it sits close to ベッド (bed) from earlier, which feels like a deliberate bit of wordplay. Then the ending stacks short pairs, "痛みと享楽" (pain and pleasure) and "学びと狂乱" (learning and frenzy), before landing on "僕らは共犯" (we are accomplices). It is cynical about the world and still oddly tender about the people in it.
Mrs. GREEN APPLE is a Japanese pop-rock band from Tokyo, formed in 2013 by vocalist and songwriter Motoki Ohmori. They made their major-label debut in 2015 with the mini-album Variety on EMI Records.
Since the start of 2022 the band has been a trio: Ohmori, guitarist Hiroto Wakai and keyboardist Ryoka Fujisawa.