Details are light (and are sourced from a Twitter account that has subsequently disappeared, so take it with a pinch
of salt), but it will
supposedly tell a «newly budding Konoha
story» and center around a group
of children.
The
supposedly secret information was hidden within the official Tomb Raider website's source code, which can be easily viewed through most web browsers, and contained relatively sensitive info such as the title and exact release date and also included info
detailing that this will be the last title
of the Lara Croft origin
story trilogy (preceded by Tomb Raider and Rise
of the Tomb Raider).