Complex sentence: Takayama assumed the position of the "wakagashira" (若頭) of the Sixth Yamaguchi-gumi on August 8,2005, one week after Tsukasa became "kumicho" (Godfather) of the Sixth Yamaguchi-gumi in July 2005.
Split into simpler sentences: Takayama assumed the position of the "wakagashira" (若頭) of the Sixth Yamaguchi-gumi on August 8,2005. Shinobu Tsukasa became "kumicho" (Godfather) of the Sixth Yamaguchi-gumi in July 2005.