かたくなに (translations)→ adamantly pious robustly staunchly stoutly stubbornly tihgtly
ひたすら (translations)→ all anxiously avidly eagerly earnest earnestly intently just literally stolidly undeviatingly unflagging
頑なに (translations)→ adamant passionately
頑固に (translations)→ firmly stubborn
執拗に (translations)→ consistently determined dog-like endlessly insistent obstinately persistent relentlessly steadily tenaciously