Thank you all for your answers
If I understand your comment correctly, you have booked:
1. first award ticket: Oslo-(via somewhere)-Hong Kong // open jaw // Tokyo-(via somewhere)-Oslo
2, second award ticket: Hong Kong-Tokyo one way by ANA.
No, not quite right. I have separate tickets for OSL-HKG and NRT-OSL with OW carrier (Finnair to be exact).I've only got HKG-NRT award tickets. I understand now, that SAS can charge me for fuel surchage themself, but question is yet how much?