Ruling Question on Strike Ninja return

1) Can you bottomless strike ninja at his return?

I understand that his return isn't consider special summon because of how the text phase it (it doesn't say S.S at end phase like D.D scout plane) Also, if IT IS a special summon, then the "once per turn" text will be meaningless because it effect will refresh as it was S.S as a new monster. (Kind of like Black luster soldier effect, after reborn, you can use the effect again as a new monster)

2) So if his return isn't a special summon, then what is his return effect call? can I still chain cards like bottomless / royal oppression to his return?

1) No, you cant bth, you have explained it yourself already
2) It's a quick effect

Further Note: If you normal strike ninja and they bth you can chain its own eff so they waste their bth

A return is called a return, it isn't a summon.