哼着那首曾经的半情曲
[hēng zhe nèi shŏu céng jīng de bàn qíng qŭ]
This username translates to 'Humming the half-love song from the past'. It evokes a sense of nostalgia for a bygone romance or lost love, with the person recalling an emotional connection through music. The term 'half-love' suggests that this memory is bittersweet and incomplete.