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We report on photometric observations of WZ Sge-type dwarf novae, MASTER OTJ211258.65+242145.4 and MASTER OT J203749.39+552210.3 which underwent outburstsin 2012. Early superhumps were recorded in both systems. During superoutburstplateau, ordinary superhumps with a period of 0.060291(4) d (MASTER J211258)and of 0.061307(9) d (MASTER J203749) in average were observed. MASTER J211258and MASTER J203749 exhibited eight and more than four post-superoutburstrebrightenings, respectively. In the final part of the superoutburst, anincrease in the superhump periods was seen in both systems. We have made asurvey of WZ Sge-type dwarf novae with multiple rebrightenings, and confirmedthat the superhump periods of WZ Sge-type dwarf novae with multiplerebrightenings were longer than those of WZ Sge-type dwarf novae without arebrightening. Although WZ Sge-type dwarf novae with multiple rebrighteningshave been thought to be the good candidates for period bouncers based on theirlow mass ratio (q) from inferred from the period of fully grown (stage B)superhumps, our new method using the period of growing superhumps (stage Asuperhumps), however, implies higher q than those expected from stage Bsuperhumps. These q values appear to be consistent with the duration of thestage A superoutbursts, which likely reflects the growth time of the 3:1resonance. We present a working hypothesis that the small fractional superhumpexcesses for stage B superhumps in these systems may be explained as a resultthat a higher gas pressure effect works in these systems than in ordinary SUUMa-type dwarf novae. This result leads to a new picture that WZ Sge-type dwarfnovae with multiple rebrightenings and SU UMa-type dwarf novae without arebrightening (they are not period bouncers) are located in the same place onthe evolutionary track.

WZ Sge-type dwarf novae with multiple rebrightenings: MASTER OT J211258.65+242145.4 and MASTER OT J203749.39+552210.3