Complex sentence: Aoki resigned from the role of Committee Chairperson on 10 July and the next day became one of the founding member's of Ozawa's new People's Life First Party, which merged with other minor parties in November 2012 to form the Tomorrow Party of Japan.
Split into simpler sentences: Aoki resigned from the role of Committee Chairperson on 10 July. A few days later Aoki became one of the founding member's of Ozawa's new People's Life First Party, which merged with other minor parties in November 2012 to form the Tomorrow Party of Japan.