旧念腐夏
[jiù niàn fŭ xià]
'Old Nostalgia Rotten Summer' reflects nostalgia for something or memories from past summer times. 'Furu' carries both meanings of being old and decaying/rotten. So, it might refer to old memories, especially during summertime which were not all rosy - a blend of good memories mixed with the bittersweet feeling.