Ladybaby will appear at an all day live event called Oretachi, Gakkyoku Ha Vol. 12, with many other idol units also playing that day (July 3rd 2017). It looks to be a great lineup.
When: Doors open: 12:00. Start: 13:00.
UPDATE: Ladybaby will appear late in the schedule at 20:20-20:40. They will then do a meet and greet at booth C from 21:00-22:00. Full schedule.
Where: Tsutaya O-East (map), a well-known live-house in Shibuya, Tokyo.
Tickets: Available on the door if the show doesn’t sell out (4000 yen + 500 yen for drink on entry). Advance tickets (3000-3500 yen) at Eplus, but this Japanese site does not accept foreign credit cards or send tickets overseas. However, if you are in Japan you can use a convenience store to pay: see this site for more information (I cannot vouch for their purchasing service as I have never used it, but the advice about buying tickets is up-to-date and correct).