ひたすら (translations)→ all anxiously avidly doggedly eagerly earnestly intently just literally stolidly undeviatingly unflagging
一途 (translations)→ particularly passionate very
固く (translations)→ absolutely heavily rigid tensely tightly
思いつめた (translations)→ burning desperate serious troubled
心からの (translations)→ dyed-in-the-wool genuinely gratuitous heart-felt heartful honest real true unalloyed warm
心底から (translations)→ fear genuine infinitely solid truly
真剣な (translations)→ anguished deeply eager grave intense nervous sincere
熱心に (translations)→ actively alertly assiduously attentively busy closely faithfully fervently hard lively seriously steadfast vigorously