Short answers, pulled from the story.
The original DWANGO service was shut down in 1998 after failing to capture the online gaming market. This event marked the end of the Dial-up Wide-Area Network Game Operation venture before Nobuo Kawakami rebuilt the company in Japan.
Niconico merged with Kadokawa Corporation on the 1st of October 2014. This merger made Niconico the primary vehicle for Nobuo Kawakami's vision of connecting creators and audiences.
Nintendo purchased 612,200 shares of Dwango in November 2013. This transaction represented 1.5% of the company and was made at the specific request of Nobuo Kawakami.
GeeXPlus was created on the 1st of July 2019 to connect Japanese brands to global influencers. This agency focuses on promotion planning, production, and distribution for digital creators.
Kadokawa Dwango reorganized its corporate structure in February 2019. During this reorganization, Dwango stopped being a subsidiary of the holding company and became a direct subsidiary of Kadokawa Corporation.
The company decided to divest its stake in Mages in July 2019. This decision allowed the company to focus on core business areas and resulted in Mages ceasing to be a subsidiary of Dwango.