Sui Ishida, creator of the Tokyo Ghoul manga, drew a 69 pages chapter of manga Hunter x Hunter, which tells a past story of the character Hisoka Morow. The new chapter was released on Thursday on Shueisha's Shonen Jump+ digital anthology and app, while the official website published an interview of Ishida and Yoshihiro Togashi, creator of Hunter x Hunter manga. The interview states why Ishida decided to draw a story about Hisoka and the impressions of Togashi after reading the chapter.

Ishida, also, published a color image of Hisoka on Twitter. Note that he is a huge fan of Hunter x Hunter and this was a dream collaboration between them. 

Sources: otakumode.com, animenewsnetwork.com