ながら == aspect ?
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～つつ
The conjunctive particle （接続詞）つつ is added to the ren’youkei of verbs. It has 3 main uses.
•simultaneous actions --------- This use is equivalent to modern <ren’youkei> ながら (while X-ing). 抱きつつ （抱きながら）（while embracing）
•repeated action
This use greatly resembles how in modern Japanese, non-stative verbs change into ～ている form when accompanied by adverbs like いつも and 毎日.
彼町に行き、衣買いつつ。（彼は町に行って、服を買う。）（He goes to town and buys clothes. [sense of repetion]）
•progressive aspect (as つつあり or with other verbs of existence)
This use indicates the progressive aspect. あり and other verbs of existence may occur in anyform. Unlike たり, which indicates the perfect aspect, つつあり indicates that there is a continuous action or state. Unlike the modern <ren’youkei> つつある pattern, this pattern doesn’t have to be used with verbs indicating change.
彼待ちつつあり。（彼は待っている。）（He is waiting.）