I made this BUR by getting a list of racehorse characters in "*_(racehorse) -horse" search, replacing the "(racehorse)" with "(umamusume)" and removing any tags that do not currently have any post, so it shouldn't create any new tags, I think.
But as Unbreakable pointed out, a lot of characters there don't have in-game character and so they don't have any tag. I'm not sure what to do with them. It feels wrong to just tag girls as racehorses, but also feels wrong to use game namespace for original characters.
The list of horses without corresponding umamusume tag:
Show
meisho_mambo_(racehorse)
ten_point_(racehorse)
meiner_wasser_(racehorse)
six_sense_(racehorse)
kauto_star_(racehorse)
simon's_shoes_(racehorse)
ocean_blue_(jpn)_(2008)_(racehorse)
greatheart_(racehorse)
meiner_emperor_(racehorse)
shahryar_(racehorse)
ekraar_(racehorse)
durezza_(racehorse)
shiraoki_(racehorse)
stars_on_earth_(racehorse)
more_than_ready_(racehorse)
do_deuce_(racehorse)
dalmary_(racehorse)
korok_(racehorse)
stay_foolish_(racehorse)
headliner_(racehorse)
meisho_samson_(racehorse)
vela_azul_(racehorse)
serifos_(racehorse)
de_laroche_(racehorse)
water_licht_(racehorse)
lilac_(racehorse)
meiner_grand_(racehorse)
kurofune_surprise_(racehorse)
rainbow_line_(racehorse)
screen_hero_(racehorse)
admire_don_(racehorse)
admire_japan_(racehorse)
hayayakko_(racehorse)
danish_field_(racehorse)
inti_raimi_(racehorse)
deep_brillante_(racehorse)
aristoteles_(racehorse)
suzuka_mambo_(racehorse)
my_own_business_(racehorse)
captain_thule_(racehorse)
hagdang_bato_(racehorse)
mystery_way_(racehorse)
she's_a_maneater_(racehorse)
sunday_silence_(racehorse)
sunline_(racehorse)
condessa_(racehorse)
champagne_color_(2020)_(racehorse)
urban_chic_(racehorse)
sabalenka_(racehorse)
goliath_(racehorse)
uberleben_(racehorse)
oriental_art_(racehorse)
curren_moe_(racehorse)
justin_palace_(racehorse)
black_caviar_(racehorse)
apapane_(racehorse)
ater_astraea_(racehorse)
efforia_(racehorse)
blue_concorde_(racehorse)
mikki_rocket_(racehorse)
refinado_tom_(racehorse)
frankel_(racehorse)
golden_sash_(racehorse)
switch_in_love_(racehorse)
danon_the_kid_(racehorse)
ask_victor_more_(racehorse)
wakia_(racehorse)
sea_the_stars_(racehorse)
african_gold_(jpn)_(racehorse)
deep_bond_(racehorse)
tastiera_(racehorse)
grace_(kor)_(racehorse)
geoglyph_(racehorse)
linamix_(racehorse)
elusive_pimpenel_(racehorse)
bal_a_bali_(racehorse)
sweep_feet_(racehorse)
soccer_boy_(racehorse)
panthalassa_(racehorse)
dear_wink_(racehorse)
fusaichi_concorde_(racehorse)
little_amapola_(racehorse)
lord_kanaloa_(racehorse)
electrocutionist_(racehorse)
schnell_meister_(racehorse)
keiai_elegant_(racehorse)
ali-royal_(racehorse)
kurofune_(racehorse)
ash_gold_(racehorse)
derma_sotogake_(racehorse)
namur_(racehorse)
meikei_yell_(racehorse)
epoca_d'oro_(racehorse)
shigeru_pink_dia_(racehorse)
plume_d'or_(racehorse)
shonan_xanadu_(racehorse)
koolinger_(racehorse)
justin_cafe_(racehorse)
american_pharoah_(racehorse)
rex_rodney_(racehorse)
naran_huleg_(racehorse)
groom_dancer_(racehorse)
equinox_(racehorse)
crans_montana_(racehorse)
to_the_victory_(racehorse)
contrail_(racehorse)
tormenta_china_(racehorse)
kane_hekili_(racehorse)
sodashi_(racehorse)
brede_weg_(racehorse)
denim_and_ruby_(racehorse)
native_dancer_(racehorse)
regaleira_(racehorse)
toho_jackal_(racehorse)
indigenous_(racehorse)
xaar_(racehorse)
mejiro_titan_(racehorse)
win_carnelian_(racehorse)
potoooooooo_(racehorse)
eclipse_(racehorse)
el_gran_senor_(racehorse)
konigsstuhl_(racehorse)
soberano_iii_(racehorse)
kizuna_(racehorse)
nijinsky_(racehorse)
sciacchetra_(racehorse)
danon_scorpion_(racehorse)
ab_leyenda_21_(racehorse)
songline_(racehorse)
masquerade_ball_(racehorse)
company_(racehorse)
dolce_more_(racehorse)
w_heart_bond_(racehorse)
lemon_pop_(racehorse)
t_m_spada_(racehorse)
danzig_(racehorse)
tout_seul_(racehorse)
bathrat_leon_(racehorse)
soul_rush_(racehorse)
titleholder_(racehorse)
agnes_surgeon_(racehorse)
verset's_jet_(racehorse)
straight_girl_(racehorse)
aoraki_(jpn)_(2020)_(racehorse)
happy_woodman_(racehorse)
gorgeous_(jpn)_(2022)_(racehorse)
tarok_(racehorse)
durandal_(jpn)_(racehorse)
danon_decile_(racehorse)
wudi_(racehorse)
kincsem_(racehorse)
ushba_tesoro_(racehorse)
croix_du_nord_(racehorse)
wishing_well_(racehorse)
byzantine_dream_(racehorse)
anilin_(racehorse)
halo_(racehorse)
daring_bird_(racehorse)
laghat_(racehorse)
lei_papale_(racehorse)
pilsudski_(racehorse)
pawlment_(racehorse)
el_tigre_mono_(racehorse)
symboli_gran_(racehorse)
agnes_flight_(racehorse)
melody_lane_(racehorse)
hear_the_drums_(racehorse)
valira_(racehorse)
mystere_(racehorse)
golden_sixty_(racehorse)
meiner_fanrong_(racehorse)
jo_cappuccino_(racehorse)
condescendance_(racehorse)
tina_thoai_lang_(racehorse)
win_bright_(racehorse)
geraldina_(racehorse)
dance_in_the_dark_(racehorse)
fantastic_light_(racehorse)
lien_de_famille_(racehorse)
maurice_(racehorse)
bashoosh_(racehorse)
total_aloof_(racehorse)
jack_d'or_(racehorse)
arkaitz_(racehorse)
smart_layer_(racehorse)
vortex_(racehorse)
stunning_rose_(racehorse)
dura_erede_(racehorse)
cosmo_nadal_(racehorse)
calandagan_(racehorse)
king_argentine_(racehorse)
whale_capture_(racehorse)
bold_pilot_(racehorse)
cheval_blanc_(racehorse)
easy_goer_(racehorse)
admire_terra_(racehorse)
benitus_di_vallerano_(racehorse)
wilson_tesoro_(racehorse)
dance_partner_(racehorse)
meteor_shower_(racehorse)
quatre_feuilles_(racehorse)
liberty_island_(racehorse)
dance_in_the_mood_(racehorse)
daiwa_major_(racehorse)
saddlers_gal_(racehorse)
museum_mile_(racehorse)
shigeru_pink_ruby_(racehorse)
cervinia_(racehorse)
queens_ring_(racehorse)
shin_emperor_(racehorse)
valixa_(racehorse)
oju_chosan_(racehorse)
meisho_tabaru_(racehorse)
meiner_leone_(racehorse)
all_american_(racehorse)
prince_rose_(racehorse)
nakayama_knight_(racehorse)
deep_sky_(racehorse)
just_a_way_(racehorse)
gold_allure_(racehorse)
gaia_force_(racehorse)
sol_oriens_(racehorse)
curren_black_hill_(racehorse)
invasor_(racehorse)
win_mighty_(racehorse)
condesaar_(racehorse)
up_to_date_(racehorse)
rocket_man_(racehorse)
delta_blues_(racehorse)
carpet_slipper_(racehorse)
win_marilyn_(racehorse)
salios_(racehorse)
yoho_lake_(racehorse)
heart's_cry_(racehorse)
northern_dancer_(racehorse)
lincoln_(racehorse)
halwa_sweet_(racehorse)
vekseli_(racehorse)
romantic_warrior_(racehorse)
goodbye_halo_(racehorse)
global_hit_(racehorse)
machaon_d'or_(racehorse)
agnes_flora_(racehorse)
yankee_rose_(aus)_(racehorse)
hakusan_moon_(racehorse)
bellagio_opera_(racehorse)
suave_richard_(racehorse)
black_tide_(racehorse)
logi_universe_(racehorse)
ouija_board_(racehorse)
cafe_pharoah_(racehorse)
niagara_nostra_(racehorse)
santorin_(racehorse)
weltreisende_(racehorse)
tokei_halo_(racehorse)
point_flag_(racehorse)
indy_champ_(racehorse)
grand_lodge_(racehorse)
fast_tateyama_(racehorse)
