It is being reported that, earlier today, Japanese retail website Rakuten Books posted a selection of listings for upcoming Nintendo proucts that have yet to be given official release dates.
Among the games listed were Mario Tennis Aces for the Switch, listed as June 22, Dillon's Rolling Western for the 3DS, listed for April 26 (the latter has yet to be confirmed for Western release) and the Pearl & Marina amiibo double pack, which was listed as having a July 13 street date.
In addition to this, a listing went up for the yet-unannounced Sushi Striker: Way of the Sushido, for both Switch and 3DS. Some of the aforementioned listings have since been removed from the website.
Nintendo have a Direct planned for later today, so its very likely that a lot of this info has hit the net a little sooner than planned. The Direct stream begins at 14:00 PT / 22:00 GMT.
Japanese Nintendo dates leaked [Siliconera]
via destructoid https://www.destructoid.com/rumour-site-leaks-japanese-release-dates-for-mario-tennis-aces-splatoon-amiibo-and-more-493282.phtml