They had a few other titles with large-ish download counts: https://www.segasammy.co.jp/english/ir/library/pdf/stockholder/2016/201603_2q_kabutsu_e6_katsudo.pdf
IIRC Hortensia is the one holding up best in revenue.
Edit:
Yes, it's one of their top 3 digital earners from Japan: https://www.segasammy.co.jp/english/pdf/release/201600803_2q_siryo_e_final.pdf
I stand corrected! I had completely forgotten about Monster Gear, yep both it and War Pirates made a big splash and quickly vanished off of Sega's reports, they only mention Hortensia Saga now true. I hadn't realised it went past 3 million downloads, what a shame that Sega's reports aren't as in depth as they were, would be easier to judge the barometer of success.
Makes me wonder if the arcade version will help push the mobile game more and keep it relevant in a way that War Pirates and Monster Gear could not.