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Star Festival (held in July or August); Tanabata; Festival of the Weaver
「織女」 has other readings with different meanings.
七夕に願い事を書く。
I write wishes on Tanabata.
七夕を祝って楽しむ。
I celebrate and enjoy Tanabata.
七夕に願い事をする。
I make wishes on Star Festival.