Ito
4-2 Hirano, SF, Hong Kong Open
4-2 Hirano, R16, Australian Open
3-4 Kato, R16, T2 Malaysia
4-1 Hayata, R32, Czech Open
4-3 Hirano, R16, Swedish Open
4-1 Ishikawa, R16, T2 Singapore
Hirano
2-3 and 3-4 Doo Hoi Kem, group and pos. 5-6, Asian Cup
1-4 Hayata, SF, Oman Open
2-4 Ito, SF, Hong Kong Open
2-4 Ito, R16, Australian Open
2-4 FTW, R16, T2 Malaysia
4-0 Sato, QF, Japan Open(who took out DN in R16)
4-1 Ishikawa, SF, Czech Open
3-1 Doo Hoi Kem, R16, ATTC singles
4-3 Hayata, R32 Swedish Open
3-4 Ito, R16 Swedish Open
0-4 Hayata, R32, Austrian Open
3-4 Lily Zhang, R16, WWC(who finished 4th)
3-4 JJH, R16, T2 Singapore(who finished 4th and 3-0 in TWC the previous week)
Ishikawa
3-4 Doo Hoi Kem, R16, WTTC
0-3 FTW, group, Asian Cup
4-1 FTW, pos. 3-4, Asian Cup
1-4 Hirano, SF in Czech Open;
1-4 Yang Xiaoxin, German Open
3-4 FTW, QF, WWC(who finished 3rd)
1-4 Ito, R16, T2 Singapore
Keep in mind Ishikawa started the year being ranked no. 3 in the world. Because of her high seeding position, Ishikawa didn't have to face anyone particularly strong, especially Ito and Hirano, in the 1st half of the year. She has run into her teammates only 7 times:
3x Kihara, R32 in Japan Open(WTP), R32 in Korea Open(WT), and R32 in Australian Open(WTP);
1x Shibata, R16 in Korea Open;
1x Sato, R16 in Australian Open;
1x Hirano, SF in Czech Open;
1x Ito, R16 in T2 Singapore
Ito has run into her teammates 12 times.
Hirano has run into her teammates 11 times.
Hayata has run into her teammates 10 times.
Hayata
4-1 Hirano, SF, Oman Open
3-4 Yoo Eunchong, R32, Qatar Open
2-4 JJH, R16, Bulgaria Open
1-4 Ito, R32, Czech Open
3-4 Hirano, R32, Swedish Open
4-0 Hirano, R32, Austrian Open