a) 扇 -> 習 -> 皇 -> 球
扇 SEN, oogi - fan
習 SHUU, nara(u) - learn
皇 KOU, OU - emperor
球 KYUU, tama - ball, sphere
b) 早 -> 古 -> 吐 -> 坪
早 SOU, SA, haya(i) , haya(meru) - early, fast, hasten
古 KO, furu(i) - old
吐 TOU, ha(ku) - spew, vomit, give vent to
坪 tsubo - unit of area