Sources: 

Yuji Horii confirmed that the anticipated live stream will take place on May 27, coinciding with the
40th anniversary of the beloved
Dragon Quest series, first launched in 1986. During this event, Horii expressed hopes to announce “the next game.”
The
livestream will not only reveal this new installment but will also include
“various other things besides the next title,” generating excitement among fans. In a previous disclosure on the KosoKoso podcast, he mentioned that this announcement is highly anticipated, emphasizing the series' deep-rooted legacy.
In addition, it’s speculated that not only is a
new mainline installment in active development, but
Square Enix plans to announce a second
Dragon Quest game later this month, marking a significant period for the franchise.
As the series approaches this milestone, fans await what
Horii and his team have in store for them in the form of new gameplay, storylines, and potential new characters, keeping the legacy of the
Dragon Quest series alive and thriving.
The livestream is expected to take place during a special event celebrating four decades of the franchise, making it a key date for RPG enthusiasts around the globe.
Sources: 
Yuji Horii announced a live stream scheduled for May 27, where he hopes to reveal details about the next _Dragon Quest_ game, marking the franchise's 40th anniversary. Alongside the game news, additional surprises will be shared during the event.