Ibusuki Hakusuikan
指宿白水館
Hakusuikan publishes no rule about tattoos anywhere on its site, and its terms of accommodation do not mention them either. What it does publish is that the rooms in the Iso wing have a hot spring bath of their own, fed from the source and left running, which answers the question for twenty rooms without anyone having to ask. The same FAQ is plain that there is no family bath here, so the Genroku-buro and the sand bath stay shared and unanswered.
Best for: A hot spring bath inside your own room, two floors above an indoor sand bath
The Iso wing holds 18 Japanese rooms and 2 Japanese-Western rooms, all with a running hot spring bath; the operator also lists the Hana wing premium rooms, Kinko-no-ma and Hakusa-no-ma, as hot spring. Other wings have plain hot water, and the operator notes that some rooms have a shower booth and no tub at all and that room assignment is left to the house, so ask for the Iso wing by name. The sand bath is indoors and connects through to the Genroku-buro, so weather never stops it: 1,540 yen a turn for guests, 15:30 to 22:00 and 6:00 to 8:30, signed for and settled at checkout. Day visitors pay 4,940 yen for the sand bath together with the Genroku-buro, 15:00 to 18:00, and cannot take the sand bath on its own.