In a small bowl over a double boiler, melt the ruby chocolate with the almond extract, almond milk, sencha powder, and salt. Let cool slightly.
While the chocolate is cooling, whip the aquafaba to stiff peaks with a Kitchen Aid or handheld electric mixer – the bowl and whisk must be completely clean and dry for this to work. Start slow and increase the speed as the peaks begin to form – the whole process will take about five minutes.
Carefully fold the chocolate into the aquafaba with a spatula and gently mix until fully incorporated – you do not want to overmix or it will deflate the mousse.
Pour into desired containers and let set overnight.