a) 炉 -> 扉 -> 輩 -> 軟
炉 RO - furnace, hearth
扉 HI, tobira - door, title page
輩 HAI - fellow, colleague, companion
軟 NAN, yawa(rakai), yawa(raka) - soft
b) 弦 -> 畜 -> 累 -> 縛
弦 GEN, tsuru - string, bowstring
畜 CHIKU - animal raising, domestic animal
累 RUI - involvement, trouble, accumulation
縛 BAKU, shiba(ru) - tie up, bind