In the latest Shonen Magazine Edge issue, released today (December 16th, 2017), a special color preview image was included. This image was included on the backside of the color page spread for Hiroyuki Takei’s Nekogahara manga series. The digital version of the magazine does not contain this image, only the print edition. The ad features a silhouette image, a URL of http://comic-sp.kodansha.co.jp/skg20th/, and the text of “2018 1. 1. OPEN!!”. Based on all this, it’s clear that Kodansha’s Shaman King 20th Anniversary website will be opening on January 1st, 2018 (1/1/2018).

Below is a partially blocked image, but was posted on Twitter by user KUROU____.

The silhouette used appears to be a new image in the similar design as Yoh from the original Shueisha volume 1 of the Shaman King manga (shown below for comparison). There are some differences, with most notably the hair which is more similar to Hana from Shaman King Flowers. It’s unclear what the “g” in the “skg20th” URL stands for.

In the Corocoro Aniki magazine issue #1, released on October 15th, 2014, Hiroyuki Takei also had a similar silhouette design to tease the announcement of his upcoming Hyper Dash! Yonkuro manga in the March 2015 issue of the same magazine. That original 2014 preview is shown below.

The original Shaman King manga started in Shueisha’s Weekly Shonen Jump issue #31 on July 20th, 1998. 2018 will be the 20th anniversary of the start of the manga and Hiroyuki Takei had previously mentioned that he hopes to have some announcements about it towards the end of this year and has begun hiring additional staff. The Shaman King Flowers manga was put on hiatus with the closing of Shueisha’s Jump X (Kai) manga magazine on October 10th, 2014. Most recently the copyrights/trademarks for Shaman King have shifted to Kodansha, and some high-end art products from Shaman King are now also containing Kodansha’s copyright.