Laws of Badminton said:§9.5 In doubles, during the delivery of service (Law 9.2, 9.3), the partners may take up any positions within
their respective courts, which do not unsight the opposing server or receiver.
Laws of Badminton said:§13.4.5 It is a fault, if in play, a player deliberately distracts an opponent by any action such as shouting or making gestures;
To add to what @phihag said, the way I understand it, the term "unsight" mostly goes for not been able to see the shuttle and the racket of the server. So even if Yamaguchi stays in front of Kolding, it would not be allowed for her to block the view of the shuttle...Technically, the receiver's partner must not block the server's view of the receiver.
In practice, unless you bring a fat giant player with Akane Yamaguchi behind him, this is not feasible, and even then, the tactical advantage would be negative.
Other than that, of course the receiver's partner must not try to distract the server:
Per §16.5.2 all players must be on court; the partner's receiver is not allowed go to the bathroom and let the receiver play singles for a while.
In summary, there are a bunch of theoretical rules touching this, but in practice, the receiver's partner can be anywhere on court, sitting, running around, or whatever – unless their antics are designed to distract the server.
TBH got faulted for moving even though he wasn't the receiver. Is this normal? Seems very strange to me.
TBH got faulted for moving even though he wasn't the receiver. Is this normal? Seems very strange to me.