with the recent addition of hassanshin (hasso induced forced zanshin attacks) ikishoten merits have some value now, currently if i land both attacks on a hassanshin proc i stand to gain around 64 tp on my masamune with ws tp return (16.9 iirc?) makes for an occasional 3 hit build.

Group 1 -
5/5 Store TP
5/5 Meditate

Group 2 -
5/5 Overwhelm
x/5 Ikishoten

not saying you should or even have to but its an interesting alternative. (x is dependent on base delay of the GKT you use) would then spend at least 1 in Shikikyo and blade bash if you have enough merits left over.