Answer:
a) 針 -> 古 -> 吐 -> 坊
針 SHIN, hari - needle
古 KO, furu(i) - old
吐 TOU, ha(ku) - spew, vomit, give vent to
坊 BOU, BO - priest's residence, priest, boy
b) 粒 -> 音 -> 明 -> 肝
粒 RYUU, tsubu - a grain
音 ON, IN, oto, ne - sound
明 MEI, MYOU, aka(rui), a(keru) - bright
肝 KAN, kimo - liver, heart, spirit