Complex sentence: JAST USA was so named because it was originally affiliated with JAST (the Japanese company), but with the closure of JAST in 2000, the company created the subsidiary Peach Princess (because there was no longer a JAST to be affiliated with).
Split into simpler sentences: JAST USA was so named because it was originally affiliated with JAST. After JAST (the Japanese company) closed shop, the company rebranded itself as Peach Princess (because there was no longer a JAST to be affiliated with).