The rule is maximum 2 stopovers in the continent of origin. If you're trying to do TYO-BLR-HKG-SIN-<somewhere> with stopovers in BLR, HKG & SIN then a OWE isn't the ticket for you. The only way the ticket would not be forfeited after no-showing HKG-SIN in that situation is if you then reissued the ticket with a transit, rather than a stopover, in SIN. If you then no-showed the outbound from SIN then the rest of the ticket would be void.