All the characters Okuu could be thinking of, and accepted nicknames.
Sections are listed in the order they appear in this game’s answer list, which is somewhat – but not quite – chronological order.
– marisa
– cirno
– meiling
– patchy/patchouli
– sakuya
– remi/remilia
– flan/flandre
– mystia
– keine
– tewi
– reisen/udongein/udonge
– eirin
– kaguya
– mokou
– chen
– alice
– lily
– lyrica
– merlin
– lunasa
– youmu
– yuyuko
– ran
– yukari
– shizuha
– hina
– nitori
– momiji
– aya
– sanae
– kanako
– suwako
– komachi
– medicine
– yuuka
– kisume
– parsee
– yuugi
– satori
– rin/orin
– utsuho/okuu
– koishi
– kogasa
– ichirin
– murasa/minamitsu
– shou
– hijiri/byakuren
– nue
– yoshika
– seiga
– futo
– tojiko
– miko
– mamizou
– sunny/sunny milk
– star/star sapphire
– luna/luna child
– sekibanki
– kagerou
– yatsuuhashi
– benben
– seija
– shimmy
– raiko
– ringo
– doremy
– sagume
– clown
– junko
– hecatia
– nemuno
– aunn
– narumi/naruko
– satono
– mai
– okina
– akyuu
– kosuzu
– iku
– joon
– shion
– urumi
– kutaka
– yachie
– mayumi
– keiki
– saki
– takane
– sannyo
– misumaru
– tsukasa
– megumu
– chimata
– momoyo
– mary/maribel/merrybel
– kasen
– miyoi
Thanks to Goblin’s Globe for his great guide, all credit to his effort. you can also read the original guide from Steam Community. enjoy the game.