Koichi Hirose was obtainable for a limited time as a collaboration character in the mobile game Puzzle & Dragons.
Koichi Hirose
広瀬康一
広瀬康一
Attributes: 
Rarity: 6★ (Base)
No. 9576
HP
3,747 (Lvl.99)
ATK
2,769 (Lvl.99)
RCV
214 (Lvl.99)
Active Skill: "Echoes ACT1"
N/A
Leader Skill: "Growth Potential"
N/A
Koichi Hirose
広瀬康一＆エコーズ ACT1
広瀬康一＆エコーズ ACT1
Attributes:
Rarity: 7★ (Transformation)
No. 9577
HP
6,206 (Lvl.99)
ATK
3,664 (Lvl.99)
RCV
439 (Lvl.99)
Active Skill: "Believe Me!"
N/A
Leader Skill: "Imbuing Objects With Voices or Sound"
N/A
Echoes ACT3
エコーズ ACT3
エコーズ ACT3
Attributes:
Rarity: 7★ (Assist)
No. 9578
HP
6,206 (Lvl.99)
ATK
3,664 (Lvl.99)
RCV
439 (Lvl.99)
Active Skill: "Echoes 3 FREEZE"
N/A
Leader Skill: "N/A"
N/A