In Japan, the day of tanabata was July 7 on the Japanese calendar such as on the Tenpo calendar (old calendar) and was celebrated mostly as a part of the Bon festival, which was held on July 15 (old calendar).
日本では天保暦（旧暦）など和暦7月7日であり7月15日(旧暦)に行われるお盆に合わせてお盆行事の一環として行う意味合いが強かった。