The Kiznaiver site just posted the official flowers the girls are holding and confirmed their meaning will help us better understand the series.
Nico: Agapanthus534Please respect copyright.ＰＥＮＡＮＡkycXXXocBS
Honoka: Zinnia534Please respect copyright.ＰＥＮＡＮＡXWRlI1DNyx
Chidori: China aster534Please respect copyright.ＰＥＮＡＮＡPTTTS61fGf
Noriko: Roses
So I did some Hana kotoba google’ ing. Here’s a brief (second) look at their meaning below the cut!
Nico
The Agapanthus is known as the “flower of love”. Its meanings include 「the arrival of (romantic) love (恋の訪れ)」, 「love letter（ラブレター）」 and 「intellectual attire/guise （知的な装い）」. It’s said that this last meaning comes from the refreshing and delicate appearance of the pale purple/blue flowers. 534Please respect copyright.ＰＥＮＡＮＡyCFdvk76jl
Source: [x]
Honoka
「thoughts of absent friends（不在の友を思う）」534Please respect copyright.ＰＥＮＡＮＡiNnQR85H5C
「I mourn your absence（あなたの不在を悲しむ）」534Please respect copyright.ＰＥＮＡＮＡizFJZpgngd
「Don't be off your guard (注意を怠るな)」534Please respect copyright.ＰＥＮＡＮＡ9jJGUkViFQ
Source: [x]
“Thoughts of friends or thoughts of a missing friend are the most common meanings for the zinnia.“ Yellow zinnias mean “daily remembrance”.534Please respect copyright.ＰＥＮＡＮＡGdnYzEKdGx
Source: [x]
Chidori
General meaning:534Please respect copyright.ＰＥＮＡＮＡo2FePjtnHS
• 「Change (変化)」534Please respect copyright.ＰＥＮＡＮＡtFY49pNbns
• 「Reminiscence (追憶)」534Please respect copyright.ＰＥＮＡＮＡA8tLSKU35d
• 「Agreement / Sympathy (同感)」534Please respect copyright.ＰＥＮＡＮＡMSzbxmu4M7
• 「Belief in (romantic) Love (信じる恋)」
Occidental meaning:534Please respect copyright.ＰＥＮＡＮＡgEUaAU5xkO
• 「Variety（多様性、変化）」534Please respect copyright.ＰＥＮＡＮＡYHbgvFYTtb
• 「Fidelity（忠実、貞節）」534Please respect copyright.ＰＥＮＡＮＡ4lU2uaZfLA
• 「I will think of you（私はあなたを想うでしょう）」
Color meaning:534Please respect copyright.ＰＥＮＡＮＡkjkgnjz2AM
• White: 「Please believe me (私を信じてください)」534Please respect copyright.ＰＥＮＡＮＡMtYlrKUoig
• Purple: 「Victory of (romantic) love (恋の勝利)」, 「My love is deeper than yours (私の愛はあなたの愛より深い)」534Please respect copyright.ＰＥＮＡＮＡtyiMKuBaMG
Source: [x]
Noriko
It’s hard to tell whether Noriko is holding orange roses or yellow ones, so I’m including both!
General meaning:534Please respect copyright.ＰＥＮＡＮＡdDtZmP9w8D
• 「Love (愛)」534Please respect copyright.ＰＥＮＡＮＡ3THTsFpEks
• 「Beauty (美)」534Please respect copyright.ＰＥＮＡＮＡcuWyNrq76t
Source: [x]
Color meaning:534Please respect copyright.ＰＥＮＡＮＡ5oKZrEmlLY
• White: 「 Purity / Chastity( 純潔)」, 「I am worthy of you (私はあなたにふさわしい)」, 「Deep respect (深い尊敬)」
• Green: 「Calm / Gentle (穏やか)」, 「You can have hope (あなたは希望を持ちえる)」
• Orange: 「Innocence（無邪気）」, 「Bonds / Kizuna （絆）」, 「Healthy（健やか）」, 「Trust / Faith （信頼 ）」.
• Yellow: 「Decrease of love（愛情の薄らぎ）」, 「Jealousy （嫉妬）」, 「Friendship （友情）」, 「Devotion （ 献身 ）」, 「Tired / Weary of (romantic) love （恋に飽きた）」.534Please respect copyright.ＰＥＮＡＮＡ00PGeE50OQ
Source: [x] & [x]
