…seem to be green again the next year… but we are not leaves.

年年歳歳
nen.nen.sai.sai

Literally: year – year – year/age – year/age

Alternately: Every single year. Year in and year out.

Notes: As always, the second instance of each character may be replaced with the kanji doubling mark 々. Also, somewhat less commonly, the order of the elements may be flipped to give 歳歳年年 (with or without doubling marks), sai sai nen nen.

This compound comes to us from a poem by Liu Xiyi (劉希夷, Japanese Ryuu Ki’i) a mid-600s CE Chinese poet. The piece, known as 「代悲白頭翁」(Japanese pronunciation “Daihi hakutouou”), laments that 年年歳歳, the flowers bloom as always – but 歳歳年年, the people who come to see them bloom are different, because old age comes for us all.

Here quoted in 『応天の門』(Outen no mon), an obscure manga about early-Heian court politics